JP2664636B2 - Local supply of heteroatoms to material surfaces - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for locally supplying heteroatoms to the surface of a substance. More specifically, the present invention relates to a method for locally supplying heteroatoms to a material surface, which is useful for creating an atomic conversion material and an atomic conversion object such as an atomic conversion device.

[0002]

2. Description of the Related Art Hitherto, with the development of advanced technologies such as electronics and biotechnology, creation of high-performance and high-performance new materials and application thereof have been promoted. In providing such a novel material, it is particularly important to supply foreign atoms on the surface of the target substance, and by supplying such heteroatoms on the surface of the target substance, The development of high-performance, high-performance new materials that are different from their original properties is expected.

[0003] Many methods have been studied and devised for supplying different types of atoms to the surface of a target substance. For example, vacuum deposition (PVD), molecular beam epitaxy, and the like have been proposed as such methods. Methods (MBE), chemical vapor deposition (CVD) and the like are well known. The vacuum evaporation method is a method in which a material is heated and evaporated in a vacuum to deposit a film on a substrate. Since the operation is easy, it is widely and generally used.

Further, molecular beam epitaxy (MBE)
Is a technique useful for producing single-crystal thin films of semiconductors, metals, and derivatives. Molecular beams generated by heating a Knudsen cell (evaporation source cell) are converted to a heated single-crystal substrate. Interacts with to form a single crystal thin film. This method enables steep interface and large area uniformity by controlling the film formation to a thickness of about one atomic layer.

Further, the chemical vapor deposition (CVD) is a method for producing a thin film using a chemical reaction as a process, and a substance generation process during growth is performed by a chemical reaction. Therefore, the M
In addition to the features of the BE method such as film formation control with a thickness of about one atomic layer, interface steepness, and large area uniformity, the CVD also enables precise composition control. These conventional gas-phase methods are common in that different types of atoms are supplied to naturally deficient portions on the surface of the target substance.

In addition, the conventional method of supplying heteroatoms to a naturally deficient portion on the surface of a target substance,
Recently, a method using a liquid metal ion source (LMIS) has been developed. In the method of supplying foreign atoms on the surface of a target substance using the LMIS, a potential is applied to a counter electrode of the needle to ionize the molten metal in the liquid phase by heating, and the generated ions are released from the tip of the needle. It is a way to make it. According to this method, it has become possible to realize a new material having more precise composition controllability.

However, in the case of these conventional methods, the controllability of the thickness of about one atomic layer, the steepness of the interface, and the uniformity of the large area can be realized, but the locality on the surface of the target substance can be realized. It is not possible to selectively supply heteroatoms to the target part. Therefore, it cannot be said that it is impossible to control the surface of the target substance at the atomic level, which is indispensable for producing new materials and devices.

The present invention has been made in view of the above circumstances, and solves the drawbacks of the prior art, and controls the surface of a target substance at the atomic level, which is indispensable for future production of new materials and devices. The purpose of the present invention is to provide a method for locally supplying heteroatoms to the surface of a new material, which enables the following.

[0009]

SUMMARY OF THE INVENTION The present invention provides a scanning tunneling electron microscope (ST) for solving the above-mentioned problems.
M) In a system comprising a microtip, a target substance, and a heterogeneous molecule for the probe and the target substance, a heterogeneous atom dissociated by a reaction between the probe surface and the heterogeneous molecule in a heterogeneous molecule atmosphere is used. A method for locally supplying heterogeneous atoms to the surface of a substance, which comprises applying a required scanning voltage to the probe to cause field-evaporation of the heteroatoms and adsorbing the heteroatoms on the surface of the target substance. I will provide a.

[0010]

In other words, in the present invention, by utilizing the surface reaction of the STM tip, heteroatoms are stored in the STM tip,
By performing the electric field evaporation, foreign atoms are locally supplied onto the surface of the target substance to be a sample. In this case, a probe of a scanning tunneling electron microscope (STM), a target substance, and a system including the probe and the target substance and a heterogeneous molecule can be configured in a container such as a chamber.

For example, FIG. 1 is a conceptual diagram showing the principle of the method for locally supplying foreign atoms to the surface of a substance according to the present invention.
As shown in FIG. 1A, the STM probe (1)
The foreign atom (2) for the target substance is stored. According to the method, an atmosphere of a heterogeneous molecule (3) is set in a chamber such as a chamber, and the heterogeneous molecule (3) is dissociated by a surface chemical reaction with the STM probe (1) to be in an atomic state to form a heterogeneous atom (2) on the surface. ) Is adsorbed and the heteroatom (2) is stored on the surface of the STM probe (1). In the case of this figure, the heterogeneous molecule (3)
Shows the case of diatomic molecules as an example, but of course, in the present invention, the heterogeneous molecule (3) is not limited to diatomic molecules.

Then, as shown in FIG. 1B, a scanning voltage is applied to the STM probe (1),
The foreign atoms (2) stored on the surface of the probe (1) are subjected to electric field evaporation. The field-evaporated heteroatom (2) is locally adsorbed on the surface of the target substance (4). In addition,
In the present invention, as shown in FIG. 2, for example, a foreign atom (2) is previously adsorbed on an STM probe (1) in a foreign molecule atmosphere, and the foreign atom (2) is discharged in the foreign molecule atmosphere. (2) may be subjected to electric field evaporation.

Then, as shown in FIG. 2B, for example, a required scanning voltage is applied to the STM probe (1), and the foreign atom (2) stored on the surface of the STM probe (1) is applied. ) Is field-evaporated and the field-evaporated foreign atoms (2)
Is locally adsorbed on the surface of the target substance (4). Of course, in the present invention, there is no limitation on the types of target substances, heteroatoms (molecules), probe materials, and combinations thereof. For example, a method of using hydrogen as a heteroatom (molecule) is extremely attracting attention as a technique for controlling the surface state of a semiconductor substrate.

The scanning voltage of the probe is not limited.
It is appropriately determined as depending on the material of the TM probe, the kind of the different molecule, and the degree of vacuum. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0015]

EXAMPLE 1 An n-type S doped with P was used as a substrate of Si (111).
15 × 7 × 0.3m from i wafer (0.1Ωcm)
Approximately 6 × 10 ^-11 using the one cut to the size of m ³
The sample was mounted on a sample holder of a scanning tunneling microscope (JEOL JSTM-4000XV) in a high vacuum state of Torr.

Then, the Si structure is repeatedly heated to 1200 ° C. at a degree of vacuum of 1 × 10 ⁻¹⁰ Torr or more to reduce the Si structure to (7 × ¹⁰ Torr).
7). Pt (platinum) containing 20% Ir was used for the STM probe. The above Si (111)-(7 ×
7) For the sample, the above 6 ×
Under high vacuum conditions of 10 ⁻¹¹ Torr and H ₂ 1 × 10
^In each case under the ^-7 Torr atmosphere, changes in the sample surface were observed from STM images.

That is, first, without considering the influence of the hydrogen molecule H ₂ , the surface of this Si (111)-(7 × 7)
The platinum probe was scanned at a high degree of vacuum of × 10 ^-11 Torr. The scanning time was 195 nm / s, and the number of scanning lines was 512. FIG. 3A shows the surface of Si when scanning is performed normally, and FIG.
As shown in FIG. Here, FIGS. 3 (a) and 3 (b)
FIG. 3 shows an area of 10 × 10 nm ² and FIG.
The part surrounded by the square in (b) is a 5 × scan of a platinum probe.
The region of 5 nm ² is shown. 3 (a) and 3 (b)
Arrows in the middle indicate spontaneous defects of Si atoms on the Si surface. In each case, the sample bias voltage was +1.
0 V and the tunnel current is 0.6 nA. This figure 3
Comparison of (a) and (b) shows that there is no significant difference between the two. This means that if there is no influence of hydrogen molecules H _2, illustrates that there is no difference in the condition of the surface.

Next, hydrogen molecules H ₂ were supplied into the chamber, and the effect on the STM image under an atmosphere of hydrogen molecules of 1 × 10 ⁻⁷ Torr was observed. The result was as illustrated in FIG. FIG. 4A shows a state before scanning.
FIGS. 4B and 4C show the state after scanning with a scanning voltage of + 3.5V. The sample bias voltage in FIGS. 4A and 4B is +
1.0 V, and the sample bias voltage in FIG.
It is.

4 (a) and 4 (b), focusing on the central portion surrounded by a square and the lower left portion of the arrow, FIG.
It can be seen that (b) is much darker than FIG. 4 (a). Similarly, for example, comparing FIG. 4 (a) and FIG. 4 (c), and focusing on the central portion surrounded by a square and the lower left portion of the arrow, FIG. 4 (c) is better than FIG. 4 (a). It turns out that it is very dark.

In this portion, a hydrogen atom H is adsorbed. Example 2 Next, a hydrogen atom H was previously attached to the tip of the Pt probe, and thereafter, the hydrogen atom was adsorbed on the Si surface in a vacuum state without supplying the hydrogen molecule H ₂ into the chamber. Was.

That is, hydrogen molecules H ₂ are continuously supplied into the chamber in advance, and 90 L (L = 1 × 10
^{At a} degree of vacuum of ⁻⁶ Torr · s), hydrogen molecules were dissociated, and hydrogen atoms H were attached to the probe surface of platinum STM. After that, the supply of hydrogen molecules H ₂ was stopped and the gas was evacuated, and the scanning voltage was set to +3.5 V in vacuum to cause the hydrogen atoms on the platinum STM probe to be adsorbed on the Si surface. FIG. 5A shows the state of the surface of the target substance before scanning.
(B) and (c) show the state of the surface of the target substance after scanning at a voltage of + 3.5V. The sample bias voltage in FIGS. 5A and 5B is +1.0 V, and the sample bias voltage in FIG. 5C is -1.0 V.

By comparing FIGS. 5 (a) and 5 (b), focusing on the central portion surrounded by a square and the lower left portion of the arrow, FIG.
5 is much darker than that of FIG. Similarly, for example, comparing FIG. 5A and FIG. 5C and focusing on the central portion surrounded by a square and the lower left portion of the arrow, FIG.
It can be seen that (c) is much darker than FIG. 5 (a).

In this portion, a hydrogen atom H is adsorbed.

[0024]

As described above in detail, according to the present invention, it is possible to provide a method for locally supplying heterogeneous atoms to a material surface at an atomic level. And, by using the generated substance to which different kinds of atoms are locally supplied, it becomes possible to apply to electronic devices and recording materials to be miniaturized, and further to application to ultra-large capacity storage devices such as atomic unit memory. Is also possible.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic views showing the principle of the present invention.

FIGS. 2A and 2B are schematic diagrams showing the principle of the present invention.

FIGS. 3 (a) and 3 (b) are photographs, instead of drawings, composed of STM images showing a state of a target substance surface as an example of the present invention.

FIGS. 4 (a), (b) and (c) are photographs, instead of drawings, composed of STM images showing the state of the surface of a target substance as an example of the present invention.

5 (a), 5 (b) and 5 (c) are photographs, instead of drawings, composed of STM images showing the state of the surface of a target substance as an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 STM tip 2 Heterogeneous atom 3 Heterogeneous molecule 4 Target substance

Claims (2)

(57) [Claims] In a system comprising a microtip, a target substance, and a heterogeneous molecule for the microtip and the target substance, a heteroatom dissociated by a reaction between the surface of the probe and the heterogeneous molecule in a heterogeneous molecule atmosphere is detected. Localized supply of heteroatoms to the surface of a substance, characterized by storing on the needle surface and then applying a required scanning voltage to the probe to evaporate the heteroatoms by electric field and adsorb the heteroatoms on the surface of the target substance Law. 2. The method according to claim 1, further comprising: storing a heterogeneous atom with respect to the fine probe and the target substance in the heterogeneous molecule atmosphere in a probe in advance, and applying a required scanning voltage to the probe while the heterogeneous molecular atmosphere is discharged. A method for locally supplying heterogeneous atoms to the surface of a substance, wherein the heterogeneous atoms are field-evaporated and the heterogeneous atoms are adsorbed on the surface of the target substance.