JP2006167857A - Micro wire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro wire having a diameter smaller than 1 nm. <P>SOLUTION: The micro wire is composed by connecting a plurality of first clusters made of a first element or by connecting a plurality of second clusters made of a second element and the first clusters made of the first element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fine wire and a manufacturing method thereof.

In recent years, application of silicon nanowires containing silicon as a constituent element to semiconductor devices and optical devices is expected. This silicon nanowire is a fine wire (quantum wire) with a diameter of the order of nanometers (nm) and electrical conductivity, and wiring in next-generation semiconductor devices and optical devices that require further miniaturization. It is promising as a material. In addition, application of carbon nanotubes is also being studied as a wiring material in next-generation semiconductor devices and optical devices.
For example, the following Non-Patent Document 1 reports production of a diameter of 1 to 7 nanometers (nm) as an example of silicon nanowires. Also, Patent Document 1 below discloses a silicon nanowire having a diameter of nanometer order and a method for manufacturing the same.
Small-Diameter Silicon Nanowire Surface, DDD Ma et al. Science 299 (2003) 1874 JP 2003-142680 A

  By the way, in the current report, the silicon nanowire having a diameter of 1 to 7 nanometers (nm) described in Non-Patent Document 1 is the thinnest. However, as a technical prospect regarding semiconductor integrated circuits, there is a view that this fine wire of about 1 nanometer is the limit until 2015, and the semiconductor integrated circuit after that requires a thinner wiring material. .

  This invention is made | formed in view of the situation mentioned above, and aims at provision of the fine wire thinner than 1 nanometer.

In order to achieve the above object, in the present invention, as a first solution for a fine wire, the first cluster composed of the first element or the second cluster composed of the second element and the first cluster A method of connecting a plurality of these is adopted.
According to the present invention, since a plurality of clusters are connected, a fine wire thinner than 1 nanometer can be provided.

As a second solution for the fine wire, in the first solution, the first and second elements are hydrogen (H), helium (He), lithium (Li), beryllium (Be), boron ( B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), neon (Ne), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus ( P), sulfur (S), chlorine (Cl), argon (Ar), potassium (K), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron ( Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), selenium (Se), bromine (Br), krypton ( Kr), Rubijiu (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), antimony (Sb), tellurium (Te), iodine (I), xenon (Xe), cesium (Cs), barium (Ba), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), Erbium (Er), Thulium (Tm), Ytterbium (Yb), Lutetium (L ), Hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), indium (Ir), platinum (Pt), gold (Au), mercury (Hg), thallium (Tl) ), Lead (Pd), bismuth (Bi), polonium (Po), astatine (At), or radon (Rn).
According to the present invention, a fine wire thinner than 1 nanometer can be formed by connecting clusters made of any one of the above elements or by connecting clusters made of different elements.

As a third solution for the fine wire, a method is adopted in which, in the first solution, the first and second elements are both silicon (Si).
According to the present invention, by connecting clusters made of silicon (Si), a silicon fine wire having a thickness smaller than 1 nanometer and having conductivity can be formed.

As a fourth solving means relating to the fine wire, in the third solving means, a means is adopted in which the first and second clusters are composed of 24 silicon (Si) atoms.
According to this invention, since the cluster which consists of 24 silicon (Si) atoms is connected, a linear silicon fine wire can be formed.

Further, in the present invention, as a first solving means related to the method for manufacturing a fine wire, in the first or second method for manufacturing a fine wire, a predetermined catalyst is placed on a silicon (Si) substrate, A method of sputtering silicon (Si) in a state is employed.
According to the present invention, it is possible to grow a cluster made of silicon (Si) on a silicon (Si) substrate, so that it is thinner than 1 nanometer made of silicon (Si) and is conductive. It is possible to easily manufacture a silicon fine wire having a property.

  As a second solution relating to the method of manufacturing the fine wire, a method is adopted in which, in the first solution, the catalyst is a transition metal. Since a transition metal is employed as a catalyst for stacking clusters made of silicon (Si) on a silicon (Si) substrate, a silicon fine wire can be easily manufactured.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As will be described later, the present embodiment relates to a silicon fine wire in which clusters having silicon (Si) as constituent atoms (that is, silicon clusters) are connected. A cluster (or atomic cluster) is a term generally indicating an aggregate of atoms composed of several to several thousand atoms, but the term cluster is also used in the present embodiment in the same meaning as this. .

FIG. 1 is a perspective view of a silicon cluster A constituting the present silicon fine wire. This silicon cluster A is a cluster composed of 24 silicon atoms 1 (Si ₂₄ cluster), and each silicon atom 1 has a bonding relationship with three silicon atoms 1 adjacent to each other to form a tetrahedron. ing. As can be seen from this figure, among the surfaces of the silicon cluster A, the hexagonal surfaces m indicated by diagonal lines are parallel surfaces facing each other in parallel. The surfaces other than the parallel surface m are pentagonal surfaces as shown in the figure. In such a silicon cluster A, the width of the largest portion is 0.8 nanometer (nm) or less.

  FIG. 2 is a side view showing a configuration of a silicon fine wire B formed by connecting six silicon clusters A. As shown in FIG. By connecting the silicon clusters A so that the parallel planes m are connected to each other, the silicon fine wire B has a linear wire shape and a diameter of 0.8 nanometer (nm) or less.

  Next, FIG. 3 is a characteristic diagram showing the stability of such a silicon fine wire B as a structure. In this characteristic diagram, the binding energy corresponding to the number of connections of the silicon cluster A is obtained by computer simulation based on the well-known first principle molecular dynamics method. As the number of connections increases, the binding energy decreases. This indicates that the stability as a structure is increased. In addition, this characteristic diagram also shows that when the number of connections is 6 or more, the decrease in binding energy tends to be substantially saturated and does not change. According to this characteristic diagram, it is shown that the silicon fine wire B in which a plurality of silicon clusters A are connected is sufficiently stable as a structure.

  FIG. 4 is a characteristic diagram showing the reactivity of the silicon fine wire B as a substance as a HOMO-LUMO gap. This characteristic diagram shows a HOMO-LUMO gap corresponding to the number of connections of silicon clusters A by computer simulation based on the first principle molecular dynamics method. As the number of connections increases, that is, a silicon fine wire As B becomes longer, the HOMO-LUMO gap decreases, indicating that the reactivity required to grow the silicon fine wire B longer increases. In addition, regarding the HOMO-LUMO gap, when the number of connections is 5 or 6, the decreasing tendency is substantially saturated and does not change.

  FIG. 5 is a characteristic diagram showing the electrical conductivity of the silicon fine wire B. As shown in FIG. This characteristic diagram is a computer simulation based on the first-principles molecular dynamics method, and obtained the density of electronic states when the silicon fine wire B has a finite length (for example, a length obtained by connecting two silicon clusters A). It is. In FIG. 5, the vertical axis indicating energy (eV) indicates the Fermi level (Fermi energy) as the reference energy (that is, energy “0”).

  Looking at the density of electronic states of the silicon fine wire B, it can be seen that the silicon fine wire B is a metal because electrons having Fermi energy exist. That is, silicon (Si) is generally known as an intrinsic semiconductor, but a silicon fine wire B formed by connecting silicon clusters A exhibits electrical conductivity as a metal. Therefore, it can be used as a wiring material for semiconductor devices.

  FIG. 6 shows the results of calculating the electronic state densities of 3s orbits and 3p orbitals of silicon (Si) atoms and the total electronic state density of the two orbitals based on the first principle molecular dynamics method. Also in this figure, the horizontal axis indicating the energy (eV) indicates the Fermi level (Fermi energy) as the reference energy (that is, energy “0”). From this calculation result, the electronic state density of the 3p orbit of the silicon (Si) atom shows a tendency similar to the electronic state density of the silicon fine wire B shown in FIG. It can be seen that the contribution of the electronic state density of the 3p orbit of silicon (Si) atoms is large.

  As described above, the silicon fine wire B is not only stable as a structure but also a fine wire having a diameter of 0.8 angstrom or less and having electrical conductivity as a metal. Therefore, this silicon fine wire B has sufficient performance as a wiring material for future semiconductor integrated circuits.

  Then, the manufacturing method of such a silicon | silicone fine wire B is demonstrated with reference to FIG. FIG. 7 is a schematic view of a sputtering apparatus for producing the present silicon fine wire B. As shown in this figure, the present silicon fine wire B is manufactured by depositing silicon atoms scattered from a silicon target on a silicon substrate on which a catalyst is placed. Here, the catalyst is a transition metal, for example, for growing silicon atoms on the silicon substrate in the form of silicon clusters A.

  According to such a sputtering apparatus (manufacturing apparatus), silicon that is a constituent atom of the silicon fine wire B can be dropped on the silicon substrate in atomic units, and each silicon atom is introduced into the above-described silicon cluster by the presence of the catalyst. The silicon fine wire B can be manufactured in the form of A, which can be successively grown on the silicon substrate, and as a result, the silicon clusters A are sequentially stacked.

  Here, as shown in FIG. 3, the silicon fine wire B has a small binding energy and is sufficiently stable as a structure. However, by optimizing the position of each silicon atom 1 in the silicon cluster A, The binding energy can be further reduced to improve stability.

  FIG. 8 is a side view of the silicon cluster A and the silicon cluster B ′ in which the positions of the silicon atoms 1 are optimized. The position of each silicon atom 1 where the internal energy is minimized is obtained by computer simulation based on the above-described first principle molecular dynamics method, and the silicon cluster A ′ thus optimized is obtained from the silicon cluster A. The internal energy is small and therefore more stable. Accordingly, the silicon fine wire B ′ (see FIG. 9) configured by connecting the silicon clusters A ′ has a smaller binding energy than the silicon fine wire B described above, and is thus more stable.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) Although the silicon fine wires B and B ′ in which the silicon clusters A and A ′ having silicon (Si) as constituent atoms are connected have been described in the above embodiment, the constituent atoms of the clusters are not limited to silicon. What are the constituent atoms of the cluster? For example, hydrogen (H), helium (He), lithium (Li), beryllium (Be), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), neon (Ne) , Sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), argon (Ar), potassium (K), calcium (Ca) , Titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga) , Germanium (Ge), arsenic (As), selenium (Se), bromine (Br), krypton (Kr), rubidium (Rb), strontium (Sr), yttrium (Y), zirconium (Zr), niobium Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin (Sn), antimony ( Sb), tellurium (Te), iodine (I), xenon (Xe), cesium (Cs), barium (Ba), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium ( Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium ( Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), oxygen Mium (Os), Indium (Ir), Platinum (Pt), Gold (Au), Mercury (Hg), Thallium (Tl), Lead (Pd), Bismuth (Bi), Polonium (Po), Astatine (At), Any of radon (Rn) may be used.

(2) In the above embodiment, all the clusters constituting the fine wire have silicon as a constituent atom, but the present invention is not limited to this. A fine wire may be formed by connecting clusters having different constituent atoms. By exchanging the target in sputtering, clusters composed of different constituent atoms can be connected and grown to produce a fine wire.

(3) In the above embodiment, using _{Si 24} cluster consisting of silicon atoms 1 24. This is because the hexagonal surfaces m that face each other in parallel are parallel surfaces, and by connecting the silicon clusters A using the parallel surfaces as butt surfaces, a linear silicon fine wire B can be formed. However, it is possible to construct a silicon fine wire by linking such silicon clusters having no parallel plane, for example, Si ₂₀ cluster composed of ₂₀ silicon atoms and Si ₂₈ cluster composed of ₂₈ silicon atoms. It is. However, the silicon fine wire in this case is curved.

It is a perspective view of the silicon cluster A which comprises the silicon | silicone fine wire concerning one Embodiment of this invention. It is a side view which shows the structure of the silicon | silicone fine wire concerning one Embodiment of this invention. It is a characteristic view which shows the stability as a structure of the silicon fine wire B concerning one Embodiment of this invention. It is a characteristic view which shows the reactivity as a substance of the silicon | silicone fine wire B concerning one Embodiment of this invention. It is a characteristic view which shows the electrical conductivity of the silicon | silicone fine wire B concerning one Embodiment of this invention. It is a characteristic view which shows the 3s orbit of the silicon fine wire B and silicon (Si) atom concerning one Embodiment of this invention, and the electronic state density of 3p orbit. It is the schematic of the manufacturing apparatus (sputtering apparatus) for manufacturing the silicon | silicone fine wire B concerning one Embodiment of this invention. In one Embodiment of this invention, it is a side view which shows the structure of the silicon cluster A 'after structure optimization. In one Embodiment of this invention, it is a side view which shows the structure of the silicon fine wire B 'which connected the silicon cluster A' after structure optimization.

Explanation of symbols

A, A '... silicon cluster, B, B' ... silicon fine wire, 1 ... silicon atom, m ... parallel plane

Claims (6)

  A fine wire comprising a plurality of first clusters each composed of a first cluster composed of a first element or a second cluster composed of a second element.   The first and second elements are hydrogen (H), helium (He), lithium (Li), beryllium (Be), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), neon (Ne), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), chlorine (Cl), argon (Ar), potassium (K), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), selenium (Se), bromine (Br), krypton (Kr), rubidium (Rb), strontium (Sr), yttrium (Y), zirconium Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), indium (In), tin ( Sn), antimony (Sb), tellurium (Te), iodine (I), xenon (Xe), cesium (Cs), barium (Ba), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium ( Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium ( Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), Reni (Re), osmium (Os), indium (Ir), platinum (Pt), gold (Au), mercury (Hg), thallium (Tl), lead (Pd), bismuth (Bi), polonium (Po), 2. The fine wire according to claim 1, wherein the fine wire is one of astatine (At) and radon (Rn).   2. The fine wire according to claim 1, wherein both the first and second elements are silicon (Si).   4. The fine wire according to claim 3, wherein the first and second clusters are composed of 24 silicon (Si) atoms.   4. The method of manufacturing a fine wire according to claim 2, wherein a predetermined catalyst is placed on a silicon (Si) substrate, and silicon (Si) is sputtered in this state. Method. The method for producing a fine wire according to claim 5, wherein the catalyst is a transition metal.

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