JPH0897152A - Method for manufacturing semiconductor thin film - Google Patents

Abstract

(57) [Abstract] [Purpose] The objective is to enable the formation of high-quality semiconductor thin films with no contamination or damage due to the dimensional accuracy of the atomic order. [Structure] The surface of the AlGaAs layer 2 has a step 162 of 2.8Å and a width 162 covered with As atoms.
It is composed of the terrace 4 of Å, and by introducing dimethylhydrazine into this, As atoms on the terrace 4 are sequentially replaced with nitrogen atoms from the end of the single molecule step 3 and the terrace 4 is replaced with a nitrogen atom from the end of the single molecule step 3. Area 5 covered, A
It is allocated to the region 6 which remains covered with s atoms. Then, introduce trimethylgallium and arsine here,
Quantum wires 7 are formed by selectively growing GaAs on the region 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor thin film for realizing an electronic functional device and an optical functional device, and more particularly to manufacturing a semiconductor quantum wire and a semiconductor quantum box. .

[0002]

2. Description of the Related Art In order to realize more sophisticated electronic functional devices and optical functional devices, further improvement of semiconductor crystal growth technology is required. Recently, with the progress of the molecular beam epitaxy method and the metal organic chemical vapor deposition method (MOCVD), a plurality of semiconductor thin films having a controllability of about a monoatomic layer in the film thickness direction are formed on a semiconductor substrate and the thin film interface is formed. A crystal growth technique having a steep heterojunction surface is being established.

Also, regarding the processing technology of semiconductor thin films,
With electron beam lithography and reactive dry etching technology, the lateral size of semiconductor thin films has progressed to the extent that they can be processed on a submicron scale. Therefore, in order to elucidate a new physical phenomenon in a semiconductor and aim at a new function, research on a quantum wire or a quantum box in which a heterogeneous semiconductor thin film of 100 angstroms or less is grown is being developed.

The following are conventional methods for manufacturing quantum wires and quantum boxes. First, a crystal of a two-dimensional structure thin film of a quantum well or a superlattice is formed on a semiconductor substrate by a vapor phase epitaxy method or the like, and then reactive ion etching is performed using a resist pattern formed by electron beam exposure by lithography as a mask. There is a method of forming a quantum wire or the like by removing unnecessary portions.
In addition, a method of forming quantum wires or quantum boxes by selectively irradiating the formed quantum well layer with a focused ion beam to modify the material has been reported (Reference: K. Kash. et al. "Optical spectroscopy of ultrasma
ll structures etched from quantum wells "Appl.Phy
S. Lett. 49, 1043 (1986)).

Further, as a semiconductor substrate, a finely inclined substrate having a surface on which crystals are formed stepwise is used, and adhering atoms are adsorbed to the stepped steps to grow crystals, whereby a vertical type is formed. There is a method of growing a superlattice (step flow growth) and using it as a quantum wire (T. Fukui and H. Sato, J. Vac. Sci. Technol. B6, 1373 (1).
988)). In addition, selective growth on the substrate surface covered with a mask such as a SiO ₂ film (reference: Y. Fukui and S. Ando, Appl.P
hys.Lett.58,2018 (1991)) has been used to try to manufacture quantum wires and quantum boxes.

[0006]

Since the quantum wires and quantum boxes have been conventionally manufactured as described above, there have been the following problems. First, in the method of using electron beam or ion beam exposure, although it can be processed into an arbitrary shape, the sample is exposed to the atmosphere when it is mounted in the processing device, so it is easily contaminated and easily damaged by the processing. There was a problem. With these methods, it has been impossible to manufacture quantum wires and quantum boxes with atomic order accuracy from the viewpoint of the processing mechanism.

On the other hand, in the production by step flow growth, when the vertical type superlattice is used for the quantum wires, it is possible to grow crystals without exposing to the atmosphere, so that it is difficult to be polluted and high quality quantum wires can be manufactured. However, due to the difference in the step flow growth mode depending on the type of attached atoms,
There was a limit in controlling the size of the thin wire with the accuracy of atomic order.

The present invention has been made to solve the above problems, and an object of the present invention is to enable formation of a high quality semiconductor thin film with a dimensional accuracy of the atomic order without contamination or damage. To do.

[0009]

According to the method of manufacturing a semiconductor thin film of the present invention, first, a compound semiconductor substrate made of a first III-V group compound semiconductor having a main surface inclined from a plane orientation (001) plane is used. While heating, a compound gas containing nitrogen atoms is introduced above this main surface to form a region in which the surface of the compound semiconductor substrate is replaced with nitrogen atoms. Then
Two or more kinds of compound gas containing an element forming the second III-V compound semiconductor having a narrower band gap than the first III-V compound semiconductor are introduced into the upper part of the main surface of the compound semiconductor substrate, Second II selectively in areas other than
It is characterized in that a semiconductor layer made of an IV compound semiconductor is formed.

Further, two or more kinds of compound gases containing the elements forming the third III-V group compound semiconductor having a band gap wider than that of the second III-V group compound semiconductor are provided on the main surface of the compound semiconductor substrate. The third feature is that the semiconductor layer is filled with a third III-V group compound semiconductor. Further, it is characterized in that the nitrogen atoms in the above-mentioned region are dissociated to expose the constituent atoms of the compound semiconductor substrate before embedding with the third group III-V compound semiconductor.

[0011]

The second III is formed on the area covered with the nitrogen atom.
-Group V compound semiconductor does not grow.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Example 1. FIG. 1 is a cross-sectional view showing a process of manufacturing a quantum wire which is an embodiment of the present invention. Hereinafter, the method of manufacturing the quantum wire according to the first embodiment will be described with reference to FIG. First, an AlGaAs layer 2 (compound semiconductor substrate) made of an AlGaAs mixed crystal is grown on a substrate 1 made of GaAs whose main surface is a plane inclined by 1 degree in the [-110] direction from the (001) plane (Fig. 1 (a)).
Although the substrate 1 is omitted in FIGS. 1B to 1E described below, the AlGaAs layer 2 is formed on the substrate 1 in FIGS. 1B to 1E as well. Is.

This growth is performed by using a support table capable of heating the substrate 1 and a semiconductor thin film growth apparatus by metal organic chemical vapor deposition (MOCVD) capable of supplying a source gas to the upper region of the support table. The temperature is set to 600 ° C., and trimethylgallium, trimethylaluminum, and arsine are supplied as source gases. Grown Al
The surface of the GaAs layer 2 reflects the state of the surface of the substrate 1 having a stepped shape, and the unimolecular step 3 having a step of 2.8Å and the terrace 4 with a width of 162Å covered with As atoms.
Consists of.

Next, the temperature of the substrate 1 is set to 500 to 600 ° C., and the partial pressure of dimethylhydrazine is set to 10 ⁻³ to 10 ⁻² Pa.
It is introduced in the range of 1 second to 10 minutes. As a result, the As atoms on the terrace 4 are sequentially replaced with nitrogen atoms from the end of the single molecule step 3, and the terrace 4 remains covered with the nitrogen atom from the end of the single molecule step 3 and the As atom. Area 6 of FIG. 1 (FIG. 1B). The ratio of this distribution is controlled by the substrate temperature, the partial pressure of dimethylhydrazine supplied, and the supply time.

Next, the temperature of the substrate 1 is set to 500 to 600 ° C., and trimethylgallium is supplied at a partial pressure of 1 Pa and arsine at a partial pressure of 70 Pa, for example. As a result, GaAs grows on the substrate 1, but GaAs does not grow on the region 5 covered with nitrogen atoms, and Ga is selectively formed on the region 6.
As grows, as shown in FIG.
A quantum wire 7 (semiconductor layer) is formed on the top. The size of the quantum wire 7 in the vertical direction is controlled by the growth time of GaAs. Further, the width of the quantum wire 7 is controlled by the distribution state of the region 5 covered with nitrogen described above.

Next, the supply of trimethylgallium is stopped and only arsine is supplied, and the temperature of the substrate 1 is increased to 650-70.
Set to 0 ° C. As a result, the nitrogen atoms covering the region 5 dissociate and evaporate (FIG. 1D), and As atoms cover the region 5 instead. Subsequently, the temperature of the substrate 1 is set to 500 to 600 ° C., trimethylgallium, trimethylaluminum and arsine are supplied,
AlGaAs is grown on the entire surface of the substrate 1.

As a result, as shown in FIG. 1 (e), the structure of the quantum wire 7 is a barrier layer 8 made of AlGaAs.
(Third III-V compound semiconductor). Although the barrier layer 8 can be formed without removing the nitrogen atoms in the region 5 described above, removing the nitrogen atoms makes the formed element more stable.

FIG. 2 is a sectional view showing a state in which the cleaved cross section of the quantum wire formed as described above is observed with a transmission electron microscope. In the figure, 21 is (00
1) A substrate made of GaAs, which is a plane inclined by 1 degree in the [-110] direction from the plane, 22 is MOCVD on the substrate 21.
Formed of Al _0.3 Ga _0.7 As
As layer, 23 is a quantum wire made of GaAs, and 24 is Al
_This is a barrier layer made of _0.3 Ga _0.7 As. Quantum wire 23
Was formed with a width of 5 nm and a height of 5 nm, and it was confirmed that the desired quantum wire structure was formed.

Example 2. In the above embodiment, (00
1) A substrate made of GaAs whose main surface is a surface inclined by 1 degree in the [-110] direction from the surface is used.
It is not limited to this. As shown in FIG. 3, (00
It is also possible to use a substrate 31 made of GaAs whose main surface is a surface inclined about 1 degree in the [010] direction from the 1) surface. In this case, a step-like step is formed in two directions on the surface of the substrate 31, and the surface of the AlGaAs layer 32 made of AlGaAs formed thereon also reflects this surface state.

On this state, in the same manner as in Example 1,
By supplying dimethylhydrazine,
A region 35 covered with nitrogen atoms is formed on the surface of the GaAs layer 32. Then, from the end of the single molecule step 33, a region 35 covered with nitrogen atoms and a region 3 still covered with As atoms
6 and GaAs is grown on this state.
GaAs selectively grows only on the region 36, and in this embodiment, the growing GaAs is formed into islands,
It becomes a quantum box.

In the above embodiment, a thin wire made of GaAs is formed on the AlGaAs layer, and AlGaAs is formed on the thin wire.
Although the barrier layer made of is formed, it is not limited to this. For example, AlAs may be used as the barrier layer, and other III-V group compound semiconductors may be used, and the above configuration does not impair the gist of the present invention.

[0022]

As described above, according to the present invention, first, a compound semiconductor substrate whose main surface is tilted from the plane orientation (001) plane is used, and a compound containing a nitrogen atom such as dimethylhydrazine is formed on the compound semiconductor substrate. By introducing gas, the surface of the compound semiconductor substrate is partially covered with nitrogen atoms. Then, following this state, a compound gas was supplied onto the heated compound semiconductor substrate to grow a semiconductor layer made of a III-V group compound semiconductor.
Therefore, the semiconductor layer does not grow in the region covered with the nitrogen atoms, but the semiconductor layer grows only in the region not covered with the nitrogen atoms, which becomes quantum wires or quantum boxes.

As a result of the above, there is an effect that the semiconductor thin film can be formed with atomic order accuracy without contacting the atmosphere on the way. Then, a semiconductor thin film with less contamination and damage can be formed, and high-quality quantum wires and quantum boxes can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a process of manufacturing a quantum wire or a quantum box in Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a cleavage cross section of a quantum wire in Example 1 is observed with a transmission electron microscope.

FIG. 3 is a perspective view for explaining a second embodiment of the present invention.

[Explanation of symbols]

1 ... Substrate, 2 ... AlGaAs layer, 3 ... Step single molecule,
4 ... terrace, 5, 6 ... area, 7 ... quantum wire, 8 ... barrier layer.

Claims (3)

[Claims] 1. A compound gas containing a nitrogen atom is added to the upper part of the main surface while heating a compound semiconductor substrate made of a first III-V group compound semiconductor, the main surface of which is tilted from a plane orientation (001) plane. A first step of forming a region in which the surface of the compound semiconductor substrate is replaced by a nitrogen atom, and a second group III-V having a band gap narrower than that of the first group III-V compound semiconductor Two or more kinds of compound gases containing an element forming a compound semiconductor are introduced into the upper part of the main surface of the compound semiconductor substrate to selectively form a semiconductor layer made of the second group III-V compound semiconductor in a region other than the region. A method of manufacturing a semiconductor thin film, comprising: a second step. 2. The method for manufacturing a semiconductor thin film according to claim 1, wherein after the second step, a third group III-V having a band gap wider than that of the second group III-V compound semiconductor is used. A third step of introducing two or more kinds of compound gas containing an element forming a compound semiconductor into the upper part of the main surface of the compound semiconductor substrate and burying the semiconductor layer with the third group III-V compound semiconductor. A method for producing a semiconductor thin film, which is characterized. 3. The method for manufacturing a semiconductor thin film according to claim 2, wherein after the second step and before the third step, nitrogen atoms in the region are dissociated to reduce the constituent atoms of the compound semiconductor substrate. A method of manufacturing a semiconductor thin film, comprising a step of exposing.