JP4854180B2 - Method for producing InSb nanowire structure - Google Patents

Description

The invention of this application relates to a method for producing an InSb nanowire structure. More specifically, the invention of this application relates to a method for producing an InSb nanowire structure that is useful as a quantum wire attracting attention in terms of miniaturization of electronic devices together with quantum dots.

  In recent years, miniaturization technology of electronic devices such as semiconductors has been rapidly advanced, and quantum dots and quantum wires have attracted attention in this process. Here, the quantum dot is a fine crystal having a size of 100 nm or less, for example, several tens of nanometers, and the quantum wire can be considered to be one-dimensionally arranged. If quantum dots are used, a high-speed quantum computer with low power consumption can be expected, and if quantum wires are used, high-performance transistors can be realized.

  Low-dimensional semiconductor nanostructure fabrication methods such as quantum dots and quantum wires include molecular beam epitaxy, crystal growth methods such as metal organic vapor phase deposition, and microfabrication techniques such as lithography and etching. So far it has been proposed.

  InSb is known as one of the materials for forming such a low-dimensional semiconductor nanostructure, and studies on the formation of quantum dots are underway. It has also been reported that dot formation changes due to irradiation with argon (Ar) ions accompanying the formation of InSb dots (Non-Patent Document 1-2).

  However, the actual situation is that there are not so many proposals and reports on semiconductor quantum wires compared to the study on the formation of quantum dots.

For this reason, it has been desired to realize a new technique that enables microfabrication that is more practical and highly reproducible as a means for forming quantum wires.
Applied Surface Science 210 (2003) 112-116 Nuclear Instruments and Methods in Physics Research B 212 (2003) 264-269

Therefore, the invention of this application focuses on the InSb has a relatively low melting point (525 ° C.), by means by a simple vapor phase method, capable of forming a useful InSb nanowire as quantum wires, and more It is an object to provide a practical method for forming a nanowire structure .

In order to solve the above problems , the invention of this application firstly forms a damage layer by irradiation with ions of impurity metal atoms on a substrate, then evaporates InSb, and at a temperature near the melting point of InSb. A method for producing an InSb nanowire structure is provided, wherein the InSb nanowire structure is self-grown and grown in the damaged layer in contact with the damage layer . Second , InSb is deposited on a substrate, and then an impurity is formed. Provided is a method for producing an InSb nanowire structure, which comprises irradiating ions of metal atoms and self-growing InSb nanowires in a portion irradiated with the ions at a temperature near the melting point of InSb.

Third, the manufacturing method according to claim 1 or 2 of the InSb nanowire structure and performing a focused ion beam irradiation of the ions of the impurity metal atoms (FIB), the fourth, the impurity metal atom ions, metal Ga, Al, a method for manufacturing one of InSb nanowire structure of claim 1 or 3, characterized in that at least one of B and Tl, the fifth, impurity metal atom The method of manufacturing an InSb nanowire structure according to any one of claims 1 to 4 , wherein the ions are Ga (gallium) ions and the substrate is silicon.

  According to the invention of this application as described above, since InSb is self-formed and grown by the entry of impurity metal atoms, an InSb nanowire structure can be realized more simply, practically and with good reproducibility. In the case of using a focused ion beam method or metal element ions such as Ga, such an effect becomes more remarkable.

  The invention of this application has the features as described above, and an embodiment thereof will be described below.

The most characteristic feature is that the InSb nanowires are grown by self-formation in the method for producing a nanowire structure of the invention of this application. This self-forming growth is made possible by making InSb a metal that is solid under normal temperature and pressure conditions as an impurity atom and entering this.

  It is considered that the metal atom in this case is selected as one that can lower the melting point (525 ° C.) of InSb. Examples of such solid elements include Ga, Al, Tl, Hf, Nb, Ta, Mo, W, V, Bi, Co, Ni, Zr, Cd, Hg, Y, La, and rare earth elements such as In, And metal elements other than Sb, B, Ge, etc. are mentioned.

  Especially, Ga, Al, B, and Tl are illustrated as a suitable thing.

  InSb nanowires can be produced by the following two methods in the invention of this application.

  <1> First, a damage layer (pattern) is formed by irradiating impurity metal ions on a substrate such as silicon, and then InSb is evaporated under vacuum and reduced pressure, and contacted with the damage layer at a temperature near the melting point of InSb. InSb nanowires are grown in a self-forming manner in the damage layer.

  <2> InSb is vapor-deposited on a substrate such as silicon by a vapor deposition method or the like, and then an impurity metal ion is irradiated in a predetermined pattern, and an InSb nanowire is irradiated at an ion irradiated portion at a temperature near the melting point of InSb. Grow self-forming.

  In any of these methods, ions may be irradiated as metal atoms or atomic groups (including compounds) as impurities, and these impurity metal ions may be irradiated by microfabrication nanofabrication. From this point of view, it is preferable to carry out by a focused ion beam (FIB) method. Further, the “near the melting point of InSb” as defined in the invention of this application means a temperature range in which at least a part of InSb is in a liquid phase. Depending on the structure, a range of ± 50 ° C. of 525 ° C., which is the melting point of InSb, can be used as a guide.

Then, heating at this temperature is performed in an atmosphere under vacuum. As the degree of vacuum, it is usually desirable to set the pressure in a range of about 1 × 10 ⁻⁵ Pa to 1 × 10 ⁻² Pa.

  In addition, in the self-forming growth of InSb thin wires, it may be considered to control the heating temperature rising / falling speed.

  In the invention of this application, InSb nanowires having a diameter of about 10 nm to 50 nm and a length of about 1 μm to 10 μm can be self-grown. And according to the said preparation method <1>, formation of a quantum wire is also attained with formation of a quantum dot.

  Therefore, examples will be shown below. Of course, the invention is not limited by the following examples.

<Example 1>
A dot pattern was formed on the Si substrate by a focused ion beam (FIB) at an acceleration voltage of 30 kV, using Ga as the ion source. Ga adhesion was confirmed in this pattern.

Into the quartz tube, the patterned Si substrate and a small bulk of InSb were charged and evacuated to a vacuum degree of 2 × 10 ⁻³ Pa. After sealing this, it heated with the electric furnace. The Si substrate was heated to 500 ° C. to 530 ° C., and the InSb microbulk was heated to 510 ° C. to 550 ° C.

FIG. 1 illustrates an SEM image of the Si substrate surface after heating. In FIG. 1, self-formed growth of InSb nanowires having a diameter of about 30 nm and a length of about 3 μm is confirmed.
<Example 2>
An InSb thin film was formed on a Si substrate by vacuum deposition. Next, this InSb thin film (130 to 250 nm) was irradiated with the same focused ion beam (FIB) of Ga ions as in Example 1 in a predetermined pattern (length 30 μm, width 100 μm, depth 10 to 180 nm).

Next, the Si substrate after ion irradiation was sealed in a glass tube in a vacuum of 2 × 10 ⁻³ Pa) and heated so that the temperature of the Si substrate was 500 ° C. to 530 ° C.

  FIG. 2 is an SEM image illustrating self-forming growth of InSb nanowires when the pattern depth is 40 nm, and FIG. 3 is an SEM image illustrating self-forming growth of InSb nanowires when the pattern depth is 60 nm.

2 is an SEM image illustrating InSb nanowires in Example 1. FIG. 4 is an SEM image illustrating InSb nanowires in Example 2. FIG. 4 is an SEM image showing another example of InSb nanowires in Example 2. FIG.

Claims (5)

Forming a damage layer by irradiating ions of impurity metal atoms on the substrate, then evaporating InSb, contacting with the damage layer at a temperature near the melting point of InSb, and self-growing InSb nanowires in the damage layer; A method for producing an InSb nanowire structure characterized by the following. InSb nanowire structure characterized by depositing InSb on a substrate, then irradiating with ions of impurity metal atoms, and self-growing InSb nanowires at the ion irradiated portion at a temperature near the melting point of InSb Method. 3. The method for producing an InSb nanowire structure according to claim 1, wherein the irradiation of the impurity metal atom ions is performed by a focused ion beam (FIB). The method for producing an InSb nanowire structure according to any one of claims 1 to 3, wherein the impurity metal atom ion is at least one of Ga, Al, B and Tl. 5. The method for producing an InSb nanowire structure according to claim 1, wherein the impurity metal atom ions are Ga (gallium) ions and the substrate is silicon.