JP3256029B2 - Embedded atomic wires and method for producing embedded atomic wires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to not only an ultra-high-density wiring technique but also a method of constructing an ultra-high-density integrated circuit combined with an element composed of a plurality of atoms.

[0002]

2. Description of the Related Art It is generally known that a conventional microfabrication technology in an integrated circuit construction technology has a minimum processing size limit of 0.1 μm. (Japanese Patent Application No. 3-340649) has been proposed. In the present invention, a switching device is configured by arranging atoms on a crystal plane, and realization of ultra-high integration and ultra-high density elements is proposed.

[0003]

In a device constituted by arranging atoms on a crystal plane, the arrangement of atoms may be disturbed by the influence of temperature or the like, and it may be difficult to obtain desired characteristics. In the state, it is an issue to make this exist stably.

[0004]

In order to realize that the above-mentioned atomic switching device is stably present on a crystal plane, in the present invention, atoms forming the device are buried in grooves formed on the crystal plane, Alternatively, by covering with another atom, a means for removing the influence of thermal disturbance or the like is provided.

[0005]

The principle of the atomic wires disclosed in the present invention will be described with reference to FIG. FIG. 1A shows an insulator or semiconductor substrate 12.
It is a top view which shows the conductive atomic fine wire 11 formed above. As shown in the cross-sectional view (b) of (a) in AA ′, the atomic wires 11 are embedded in the grooves formed on the crystal surface of the substrate 12 and can stably exist on the substrate surface. This is the smallest electronic circuit component conceivable in principle.

[0006]

【Example】

(Embodiment 1) This embodiment discloses a method for realizing an atomic wire. Atom manipulation is performed by a scanning tunneling microscope (ST
M) (for details on STM, for example,
G. Binnig, H. Rohrer, Ph. 49, 57, 1982, Physical Review Letters
ys. Rev. Lett., 49 , 57 (1982)). In the STM, individual atoms can be extracted from the crystal surface by a voltage applied to the probe in a state where the probe and the sample substrate are brought close to each other until a tunnel current is detected. For example, it has been reported that molybdenum disulfide (MoS ₂ ) can extract S atoms on the crystal surface by applying a voltage pulse of −5.0 V to the probe (S. Hosoki, Applied Science, Inc.). -Fes Science,
60/61, 643, 1992 (S. Hosoki, Appl.Surf.Sci., 60/61 , 6
43 (1992))). When weakly bonded adatoms are present on the substrate surface, it is also possible to induce surface diffusion by applying a voltage to the probe and to draw the adatoms directly below the probe. For example, gallium arsenide (GaAs)
s) It has also been reported that cesium (Cs) atoms adsorbed on a substrate collect under a probe when a pulse of -3.0 V is applied to the probe (El J. Whitman, Physical. Review Letters Volume 66 1338 (1991)
Year (LJ Whitman, Phys. Rev. Lett., 66 , 1338 (1991)).

A procedure for actually realizing an atomic wire will be described with reference to FIG. 2 (a1) (b1) (c1)
(D1) is a plan view of the substrate crystal seen from above, and (a)
2) (b2), (c2) and (d2) are (a1)
It is sectional drawing in AA 'of (b1) (c1) (d1). First, the surface atoms of the atoms 21 constituting the substrate crystal are extracted, and the narrow grooves 22 as shown in FIGS.
To form Atom 2 shown by a thick line in the plan view of FIG.
Reference numeral 1 denotes a substance existing on the surface, and a substance other than that represents a substance existing in the second or lower layer.

Next, the atoms 23 constituting the atomic fine wire are adsorbed on the substrate surface (FIGS. 2 (b1) and 2 (b2)). This atom 23 is embedded (FIG. 2 (c1) (c
2)). Further, the probe is moved from the narrow groove 22 to another region, a voltage pulse is applied again, and the adatoms 23 left near the narrow groove 22 are diffused to other regions, thereby removing the adatoms 23 from the vicinity of the narrow groove 22. Remove. Since the adatoms 24 embedded in the narrow grooves 22 are in more contact with the substrate atoms and are more stable than the adatoms 23 on the substrate, as a result, only the adatoms 23 on the substrate are diffused. Removed
The adsorbed atoms 24 in the narrow groove 22 are arranged and remain in a fine line shape.
The atomic wires 25 as shown in (d1) and (d2) are formed.

In general, the shape of an atomic wire need not be a single straight line, but the most stable shape due to the interaction between the substrate and the fine wire atoms, for example, a zigzag structure as shown in FIG. Such a chain composed of a plurality of fine wire atoms 32 may be formed on the crystal substrate 31. In FIG. 3, FIG.
Like the plan view, the atoms 31 indicated by thick lines represent those present on the surface, and those not present represent those present in the second and lower layers. In the present embodiment, the state is shown in which the fine wire atoms 32 are regularly arranged, but the same effect can be obtained by random arrangement.

The atomic radius of the fine wire atom 24 is optimal when it is almost equal to the width of the fine groove 22. However, even when the atomic radius is larger than the groove width, it can be embedded in the groove. Closely packed.

Since the STM cannot be applied to an insulating sample, a specific method of realizing the buried atomic wires is to use a semiconductor such as silicon (Si) as a substrate, for example.
By forming an atomic wire at room temperature using an alkali metal such as cesium (Cs) as a conductive atom and cooling it to, for example, liquid nitrogen temperature (77K),
It is possible to use only the substrate in an insulated state.
As the substrate temperature, an appropriate value between several μK and several hundred K can be selected depending on the conductivity of the substrate and the atomic wires.

(Embodiment 2) In this embodiment, an embodiment relating to an atomic wire using a plurality of types of atoms will be described. The fine wire atom is not limited to one kind, and a plurality of kinds of atoms may be used. By using a plurality of types of atoms having different chemical or physical properties, the conductivity of an atomic wire is changed, or an element which requires a plurality of atoms having different transfer characteristics as shown in Embodiment 3 is constructed. It becomes possible. When using multiple types of atoms in a single atomic wire, first fill the narrow groove with one type of fine line atom, extract the required number of fine line atoms, adsorb and diffuse different types of fine line atoms, and then re-enter the fine groove. Fill. By repeating this, it is possible to realize an atomic wire composed of any kind of atoms. As another method, an atomic wire composed of a plurality of atomic species can be realized by adsorbing a plurality of atomic species on the substrate surface and applying a voltage pulse to the probe. Further, by simultaneously burying a plurality of types of atoms which are likely to form bonds with each other in the groove, an atomic wire having a constant composition can be formed.

FIG. 4 shows an example of an atomic wire including two types of atoms 42 and 43 formed on a substrate crystal 41. Also in this case, the sequence may have a zigzag structure, a multi-chain structure, or a random structure. In FIG. 4 as well, the atoms 31 indicated by thick lines represent those existing on the surface, as in the plan view of FIG. 2, and those not present represent those existing in the second and lower layers.

(Embodiment 3) In this embodiment, a configuration of a switching element to which an atomic wire is applied will be described. FIG. 5 shows an example of the switching element. FIG. 5 shows only the outermost surface atoms. Atomic wires 51, switching electrodes 52 and 53, switching atoms 54, guide atoms 5
5 and substrate atoms 56. The electrode 52 has Hig
One of the h voltage and the Low voltage is applied, and an intermediate value between the two voltages is always applied to the electrode 53.
The direction of the electric field generated between the two electrodes changes depending on the voltage applied to 2. Further, a switching atom 54 is disposed between the two electrodes, and if a switching atom 54 having a relatively small interaction with the switching atom 54 is selected as a guide atom 55 adjacent thereto, the switching atom 54 moves between the two electrodes by an electric field. It becomes possible. The movement of the switching atoms 54 exerts a switching action on the atomic wires 51.
That is, when the switching atom 54 is in the atomic wire 51, it is in the ON state (FIG. 5A).
The state (FIG. 5B) is shown. Also, without applying an intermediate voltage to the electrode 53, a high voltage is applied to the electrode 52 to move the switching atom 54 to be turned on, and a high voltage is applied to the electrode 53.
It is also possible to turn off by applying the h voltage. The switching atom 54 may be plural, and the atom wire 51
May be the same kind of atoms as the atoms constituting Further, the guide atoms 55 may be the same type of atoms as the substrate atoms 56. For example, as the substrate, a semiconductor such as silicon (Si), gallium arsenide (GaAs), molybdenum disulfide (MoS ₂ ), or an insulator such as aluminum oxide (Al ₂ O ₃ ) or magnesium oxide (MgO) is used. Metal wires such as sodium (Na), magnesium (Mg), gold (Au), iron (Fe), and copper (Cu) are used as the fine wires, but they basically exhibit conductivity. Any material may be used. In particular, good characteristics were obtained when gold was used. As the switching atoms, atoms that can easily move on the surface can be used. For example, metal atoms such as potassium (K) and cesium (Cs), or xenon (X
An atom having a small interaction with the substrate such as e) is suitable.
As the guide atoms, a semiconductor or an insulator is appropriate as in the case of the substrate. Good switching characteristics were obtained when an atomic wire composed of gold (Au) atoms was formed on a silicon (Si) substrate, and cesium (Cs) was used as switching atoms and silicon (Si) was used as guide atoms. .

(Embodiment 4) This embodiment discloses an embodiment of an atomic wire in which the surface is covered with another atom. FIG. 6A is a cross-sectional view taken in parallel to the atomic thin line 63, and FIG. 6B is a cross-sectional view taken in a direction perpendicular to the atomic thin line 63 in AA ′. With respect to the atomic wires 63 embedded in the crystal surface formed by the substrate atoms 61, the surface is further covered with insulating atoms 62, whereby it is possible to configure the atomic wires 63 completely buried from the surface. Thereby, the atomic wires 63 are further stabilized. For example, gold (Au) as the atomic wire 63,
Metals such as silver (Ag), copper (Cu), cesium (Cs),
As the insulating atoms 62, an insulator such as a metal oxide, a metal nitride, an organic carbon compound, and fullerene (C ₆₀ ) can be used. Further, the arrangement of the atomic wires 63 may be a zigzag structure, a multi-chain structure, or a random structure, and the insulating atoms 62 may be a multilayer. The fullerene (C ₆₀ ) can also be used as a conductor material by doping an alkali metal.

(Embodiment 5) In this embodiment, an embodiment relating to laminated atomic wires will be disclosed. FIG. 7A shows an atomic wire 74.
And (b) is a cross-sectional view of AA ′ taken in parallel with the atomic wire 73. In this method, an atomic wire 73 formed on a substrate crystal 71 is covered with insulating atoms 72, and an atomic wire 74 is further formed thereon to form an insulating atom 7.
5 shows an example of a laminated atomic thin wire constituted by coating with No. 5. The insulating atoms 72 and 75 may be the same kind of atoms and molecules. By repeating this, it is possible to obtain a laminated structure of an arbitrary number of layers, and it is also possible to arrange the device described in the third embodiment on each layer. At this time, the atomic wires between the layers must be separated at least so as not to cause any interaction. According to the studies by the inventors, the distance between the layers must be at least 1 nm,
In particular, it has been found that good insulating properties are exhibited when a distance of 1.4 nm or more is provided.

In the above embodiment, the fine atomic wires are formed in the grooves excluding the atoms constituting the substrate crystal. However, the substrate is not necessarily required to be a crystal.
It may be amorphous, as in iO ₂ ). In this case, the atomic wires do not always have a linear structure, and may have an irregular structure.

In the above embodiment, the structure in which the substrate crystal is composed of a single atom is disclosed.
It is also possible to use a substrate composed of a plurality of types of atoms such as aAs) and aluminum oxide (Al ₂ O ₃ ).

Embodiment 6 This embodiment discloses an example in which a plurality of atomic wires formed in different layers are electrically connected to each other in the laminated atomic wires shown in Example 5. FIG.
(A) is a sectional view parallel to the atomic wires 84 and 85, and (b) is a sectional view along AA '. In the same manner as in Example 5, an atomic wire 85 is formed on the crystal surface constituted by the substrate atoms 81, and this is covered with an insulating atom 82.
4 is formed and further covered with insulating atoms 83. In the laminated atomic wires, the atomic wires 84 and 85 are electrically connected by the atomic wires 86, whereby the electrical connection between the respective layers is established. It is possible to get. The atoms constituting the atomic wires 84, 85 and 86 may be the same kind of atoms, and the insulating atoms 82 and 83 may be the same kind of atoms.

(Embodiment 7) In this embodiment, two layers in the same layer
An example of the intersection of atomic wires in a book is disclosed. 9A is a cross-sectional view parallel to the atomic wires 95 and 96, and FIG. 9B is a cross-sectional view along AA ′. When atomic wires 94 and 95 crossing each other are present on the crystal surface constituted by the substrate atoms 91, a bridge structure is formed by the atomic wires 96 and 97 using the atomic wire connection method between layers described in the sixth embodiment. By doing so, it is possible to realize an intersection of atomic wires without any electrical interaction. The insulating atoms 92 and 93 may be the same kind of atoms, and the atoms constituting the atomic wires 94, 95, 96 and 97 may be the same kind of atoms.

[0021]

According to the atomic wires according to the present invention, a circuit with a much higher density can be constructed as compared with an integrated circuit using a conventional process.

[Brief description of the drawings]

FIG. 1 (a) is a view of an embedded atomic wire according to the present invention.
(B) Sectional view of the atomic wire in AA '.

FIG. 2 is a view showing a procedure for producing an atomic wire. (A1) (b
1) (c1) and (d1) plan views. (A2) (b2) (c
2) (d2) (a1) (b1) (c1) (d
Sectional drawing in AA 'of 1).

FIGS. 3A and 3B show examples of atomic wires. FIG.

FIG. 4 is a diagram showing an example of an atomic wire using a plurality of types of atoms.

FIG. 5 shows an example of an atomic-level switching element.

FIG. 6 is a diagram showing an example in which the surface of an atomic wire is covered.
(A) Plan view. (B) Sectional drawing in AA '.

FIG. 7 is a view showing an example of a laminated atomic wire. (A) Plan view. (B) Sectional drawing in AA '.

FIG. 8 is a diagram showing an example in which atomic wires in different layers are connected. (A) Sectional drawing. (B) Sectional drawing in AA '.

FIG. 9 is a diagram showing an example of the intersection of atomic wires. (A) Sectional drawing. (B) Sectional drawing in AA '.

[Explanation of symbols]

11, 25, 51, 63, 73, 74, 84, 85, 8
6, 94, 95, 96, 97; atomic wires, 12; substrate crystal, 21, 31, 41, 56, 61, 71, 81,
Reference numeral 91: substrate atom, 22: atomic fine groove, 23; adatom, 24, 32; fine atom, 42; fine atom 1,
43; fine wire atoms 2, 52, 53; switching electrode,
54; switching atom 55: guide atom 6
2, 72, 75, 82, 83, 92, 93; insulating atoms

Continuation of front page (56) References JP-A-5-175513 (JP, A) M. Eigler, et al, Positioning single atoms with a scanning tunneling microscope, NATURE Vol. 344 pp. 524-526 (1990) Shigeyuki Hosoki, et al., Surface modification of MoS2 using an STM, Applied Surface Science 60/61 pp. 643-647 (1991) Yasuo Wada, et al., A proposal of nanoscale devices base on atom / molecule switching, J. Mol. Appl. Phys. 74 (12) pp. 7321-7328 (1993) Ken-ichi Tanaka, Atomic-Scale Chemistry of Metal Surfaces, Jpn. J. Appl. Vol. 32 pp. 1389-1393 (1993) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 29/06 H01L 21/20 H01L 21/3205 H01L 29/66 JICST file (JOIS)

Claims (5)

(57) [Claims] 1. A structure having a structure in which a plurality of conductive atoms are buried in a groove formed on a semiconductor substrate and having a depth and a width corresponding to one or more atoms, and which can stably exist on a crystal plane. A thin atomic wire, characterized in that: 2. The buried atomic fine wire according to claim 1, wherein the atomic fine wire formed in the groove of the semiconductor substrate has a structure in which the surface is covered with non-conductive atoms. 3. A method according to claim 1 , wherein a plurality of atomic wires are formed on the surface of the semiconductor substrate.
2. The buried atomic wire according to claim 1, comprising a layered structure formed in a direction perpendicular to the surface of the substrate. 4. The buried atomic wire according to claim 1, wherein said semiconductor substrate is a crystal substrate. Preparing a 5. substrate, the step of forming a groove pull the surface atoms forming the substrate with the substrate scanning tunneling microscope, a step of adsorbing the atoms to move to the groove, the Burying the atoms adsorbed in the groove portion.