JP4922566B2 - Manufacturing method of nanowire - Google Patents

Description

The present invention relates to a method for producing nanowires.
Note that in this specification, the nanowire refers to a linear structure having a thickness of several nanometers to several tens of nanometers and an aspect ratio (length ratio to thickness) of 10 or more.

  Since nanowires have a one-dimensional structure, their physical properties are easy to explain theoretically and accurately. Therefore, there is a possibility that the theory of physical properties can be verified and nanowires can be theoretically designed in the future, which is very interesting.

In addition, for next-generation ultra-large scale integrated circuits, nanometer-sized electronic elements are required, and nanowires are also required for this purpose. In addition, it opens the way to the creation of single-electron devices, quantum computer memories, neural circuits, etc. that flow electrons one by one through nanowires.
Thus, nanowires have not only theoretical interest but also the potential for industrial use.

  For research purposes where the theory contrasts with experiments, nanowires that are relatively short (eg, on the order of tens of nanometers) may be sufficient. However, when used industrially, such as in the manufacture of electronic devices, nanowires that are sufficiently long (for example, a length of about several micrometers) are required.

  In a standard semiconductor processing process, the linear structure is formed by combining processes such as thin film formation, lithography, and etching. Combining these standard semiconductor processing processes to form a linear structure with a thickness on the order of nanometers, it is necessary to shorten the wavelength of the light beam used or the beam diameter of the electron beam. Advanced technology is required.

  At the current standard of standard semiconductor processing processes, it is only possible to create nanowires with a thickness of nanometers, and it is possible to reliably create nanowires with a thickness of nanometers and a length of several microns. There is no known way to do it.

  Patent Document 1 discloses a method of manufacturing nanowires of various substances by self-assembly. In the method disclosed herein, nanowires are formed by self-assembly by dissolving these substances in a first solvent and dropping the solvent onto the surface of a second solvent that does not dissolve the substances. .

Non-Patent Document 1 discloses that ErSi ₂ can be formed on the [001] surface of Si by a self-organization process.

Furthermore, 2a-Pa-27 on page 1221 of Non-Patent Document 2 is entitled “Self-organized NdSi ₂ nanowires prepared on a Si substrate”. Is reported to have reached 25 μm.

Similarly, 2a-Pa-28 on page 1222 of Non-Patent Document 2 titled “Dependence of surface orientation of self-organized NdSi ₂ nanowires formed on Si substrate”, nanowires were prepared by laser ablation method. And the dependence of crystal growth on the plane orientation has been reported.

Further, Non-Patent Document 3 discloses that when erbium silicide (ErSi ₂ ) is grown on the [001] surface of Si, nanowires are formed by self-organization. A model is shown in which nanostructures are self-formed on a solid surface. This can be briefly summarized as follows.

_Let D _{sm be} the chemical bond force between the substrate and the thin film atoms, and D _mm be the chemical bond force between the thin film atoms. At this time, if D _sm > D _mm , a layer having a planar structure is formed one by one on the substrate. If D _mm <D _sm , crystal nuclei are first formed on the substrate, and finally they combine to form a thin film. If D _sm >> D _mm and there is a large mismatch between the crystal lattice constants of the substrate and the thin film, the first layer covers the substrate as much as possible. Thanks to the first layer, the second and subsequent layers are not affected by the substrate. However, the strain caused by lattice constant mismatch increases as the film thickness increases. Due to this strain, a pyramid structure is formed or a wire is formed due to strain anisotropy.

Japanese Patent Laid-Open No. 2003-71799 "Self-assembled growth of epitaxial erbium disilicide nanowire on silicon (001)" by Yong Chen et al [Applied Physics Letters Vol 76, Number 26, (26 June 2000) Page 4004-4006] Proceedings of the 65th Annual Meeting of the Japan Society of Applied Physics (Fall 2004) (JSAP Catalog Number AP 041136-03) Website “www.nanoelectronics.jp/kaitai/selfassemble/8.htm”

  However, depending on the conventional disclosed technologies as described above, it has not been possible to efficiently and reliably manufacture nanowires having a thickness of several nanometers to several tens of nanometers and a length of 1 micrometer or more. .

  The present invention has been made in view of the above-described background art. Nanowires having a thickness of about several nanometers to several tens of nanometers and a length of 1 micrometer or more are efficiently formed by self-assembly, and It is an object to propose a method for reliably manufacturing.

The above-described problems have been solved by the nanowire manufacturing method according to the present invention described in claim 1.
Specifically, a substrate preparation process for preparing a substrate having a clean crystal surface, a nanowire material preparation process for preparing a nanowire material that forms nanowires by self-organization on the substrate, and the nanowire material described above In a nanowire manufacturing method including a material supply process for attaching to a surface of a substrate and an annealing process for maintaining the substrate to which the material is attached at a predetermined temperature in a vacuum, the surface of the surface of the substrate to which the nanowire material is attached is provided. A method for producing nanowires, characterized in that a microspace formation process for forming a microspace is provided in advance, and the annealing process is performed in a state where the microspace is formed in front of the surface of the substrate to which the nanowire material is attached. Solved by.
As a nanowire material capable of forming a nanowire by self-assembly, a rare earth element such as Er, Nd, Yb, a 3d transition metal element such as Ni, Mn, Cr, Co, or a compound or alloy of these and Si, or , Ge or GeEr, or a compound or alloy containing them.

  Here, in the present invention, the surface of the substrate is a [100] plane, a [110] plane, or a [111] plane of a single crystal of Si, and the material supplying process is performed by a spin coating method. A process in which a solution in which a material for manufacturing the nanowire is dissolved is applied to the surface of the substrate using a spin coater, or laser irradiation is performed with the material for manufacturing the nanowire as a target by the laser ablation method. It is a preferable embodiment to consist of the process of adhering the above material to the surface of the film.

  Further, the micro space forming process is performed by placing a spacer provided with a hole in front of the surface of the substrate to which the material is attached, and further covering the hole of the spacer with a lid member to form a micro on the front surface of the substrate. A spacer type micro space forming process for forming a space, or a covering member formed with a shallow recess is placed so that the recess is positioned in front of the surface of the substrate to which the material is attached. Consisting of a concave microspace forming process for forming a microspace on the front surface of the substrate is a preferred embodiment because the microspace can be easily and reliably formed.

  Further, in the annealing process, the substrate is heated from the side of the substrate opposite to the surface on which the material is adhered, and in the annealing process, the temperature of the substrate is changed to a material for forming the nanowire. Keeping the temperature higher than the evaporation temperature of the nanowire and slightly lower than the evaporation temperature of the constituent elements of the nanowire is a preferred embodiment for producing the nanowire efficiently and reliably by self-assembly. .

Further, the nanowire material is a rare earth chloride such as ErCl ₃ , and the heating temperature of the substrate in the annealing process is 1000 to 1200 ° C., or the nanowire material is a rare earth chloride such as ErCl ₃ . , a decomposition temperature heating temperature of the substrate is of the rare earth chloride in the annealing process, it is a two-step wire generation temperature of 1000 to 1200 ° C., both of which are preferred embodiments.

  According to the present invention described above, a nanowire having a thickness of several nanometers to several tens of nanometers and a length of 1 micrometer or more can be efficiently and reliably manufactured by self-assembly, Nanometer-sized electronic devices can be created.

Hereinafter, a preferred embodiment of the above-described method for producing a nanowire according to the present invention will be described in detail by taking a case of producing an ErSi ₂ nanowire as an example. However, the present invention is not limited to this embodiment. Is not to be done.

In this embodiment, a single crystal of Si is used as the substrate. Furthermore, [100] plane, [110] plane, and [111] plane are used as clean crystal planes.
Since the method for forming these clean crystal faces of the Si single crystal is known and is a common technique, its description is omitted here.

Next, the nanowire material is attached to the clean crystal face (hereinafter sometimes simply referred to as “surface”) of the substrate. This nanowire material is a material element or material molecule that becomes a nanowire by a chemical reaction in the subsequent annealing process. In this embodiment, a Si target material containing ErCl ₃ or Er is used.

In a first embodiment in which a nanowire material is attached to the surface of the substrate, a material for making a nanowire (ErCl _{3 in} this example) is formed by spin coating using a spin coater. Apply on top.
The spin coating method is a method in which a solution is dropped on a substrate fixed on a rotating table, and the substrate is thinly coated with the solution by centrifugal force.

FIG. 1 is a conceptual diagram of the spin coating method.
A nanowire material 1 (in this example, ErCl ₃ powder) is dissolved in a solvent 2 (for example, an alcohol such as ethyl alcohol) to form a saturated solution 3. Then, the substrate 4 is fixed on the substrate support 5, and the prepared saturated solution 3 of nanowire material is dropped onto the crystal face 4 a of the substrate 4 while rotating the substrate support 5.

The dropped saturated solution 3 spreads thinly on the crystal surface 4a of the substrate 4 by centrifugal force. By drying this, the nanowire material 1 (ErCl ₃ ) can be uniformly deposited on the clean substrate 4. At this time, the surface density of the material 1 on the substrate 4 can be changed by changing the degree of dilution of the saturated solution 3 to be dropped or changing the amount of dripping.
This process can be performed in an air atmosphere.

As a second embodiment in which the nanowire material is attached to the surface of the substrate, the material 1 for making the nanowire (in this example, a Si target containing Er) is crystallized using the laser ablation method. Laminate on top.
The laser ablation method is a technique in which a target is irradiated with a high-energy pulsed laser beam, and the target material is evaporated or ionized to evaporate and laminated on the surface of a substrate disposed facing the target.

FIG. 2 is a conceptual diagram of the laser ablation method.
A substrate 4 made of Si single crystal is fixed to a substrate support 5 and a target 6 is fixed at a position facing the substrate 4. In this embodiment, the target 6 is a pellet obtained by hot pressing a mixture of Si and Er powder. The target 6 is irradiated with a high energy pulse laser beam 7 generated by a YAG laser (not shown) or the like. Due to the energy of the laser beam 7, the substance in the target 6 evaporates by being evaporated or ionized as indicated by 8 in the figure, and is laminated on the surface 4a of the substrate 4. In this way, an amorphous Si layer containing Er as a nanowire material can be deposited on the clean substrate 4. At this time, the amount of Er and Si on the substrate 4 can be adjusted by adjusting the ratio of the amount of Si and Er in the pellet, for example, by changing Er to 0.2 wt% to 30 wt%. .

  The spin coating method and the laser ablation method have been introduced as methods for depositing the nanowire material 1 on the clean substrate 4, but the technical scope of the present invention is not limited to these methods. It is also possible to attach the nanowire material 1 to the surface 4a of the substrate 4 using other methods such as vacuum deposition.

In the past (for example, the nanowire manufacturing method described in Non-Patent Document 2 above), the substrate 4 on which the material such as ErCl ₃ is adhered is simply heated in vacuum as described above. Was creating nanowires.
However, this method has been found to be very inefficient. The reason for this is that when the substrate is heated to anneal, the material that forms the nanowires evaporated from the substrate surface into the vacuum is stacked on the wall surface of the vacuum vessel, and the amount returned to the substrate again is reduced. . In addition, nanowire formation by self-organization is achieved by a very delicate physicochemical equilibrium, but when the volume of the vacuum space is large, the physicochemical equilibrium is difficult to achieve and the process of self-organization This is thought to be because it is difficult to maintain a stable state.

  Therefore, in the present invention, this problem is solved by forming a minute space with a minute thickness in front of the surface of the substrate to which the material is attached.

FIG. 3 is a conceptual diagram of a first method (spacer type microspace formation) for creating a microspace.
A small hole 9a is formed above the substrate 4 on which the nanowire material 1 (in this example, a thin film of Si containing ErCl ₃ or Er) is attached by the spin coating method of FIG. 1 or the laser ablation method of FIG. The perforated spacers 9 are stacked, and the lid member 10 is stacked so as to close the holes 9a. As a result, as shown in FIG. 4, a minute space S is formed on the surface 4a of the substrate 4 to which the nanowire material 1 is attached.

  The thickness of the minute space S can be adjusted by changing the thickness of the spacer 9. By forming the spacer 9 as a thin film or a thin plate, the thickness can be easily changed from several micrometers to several millimeters. The hole 9a can be formed by a known technique by cutting a thin film with a cutter or using etching. The lid member 10 only needs to cover the hole 9a portion of the spacer 9. It is not necessary to bond between the substrate 4 and the spacer 9 and between the spacer 9 and the lid member 10.

FIG. 5 is a conceptual diagram of a second method for forming a minute space (recessed minute space formation).
In this method, the covering member 11 in which the concave portion 11a is formed is overlaid on the surface 4a of the substrate 4 to which the nanowire material 1 is attached. As a result, as shown in FIG. 6, a minute space S is formed on the front side of the surface 4 a to which the nanowire material 1 of the substrate 4 is attached.

  The thickness of the minute space S can be adjusted by changing the depth of the recess 11a. The recess 11a of the covering member 11 can be formed by a known technique such as etching, and the depth can be easily adjusted. The substrate 4 and the covering member 11 need not be bonded.

  As described above, as a method of creating the minute space S, the method using the spacer 9 having the hole 9a and the lid member 10 and the method using the covering member 11 having the recess 11a have been introduced. However, the technical scope of the present invention is as follows. However, it is not limited to this. For example, it is possible to eliminate the spacer 9 and only hold the substrate 4 and the lid member 10 at a narrow interval, so that the minute space S is a narrow space that spreads in two dimensions. The important point is to reduce the space facing the part to which the nanowire material 1 is attached. The most preferable range of the thickness of the minute space S is about 5 to 600 micrometers.

  In this specification, the nanowire material 1 is attached to the substrate 4 and the minute space S is formed in the portion facing the nanowire material 1 is called a sample. Therefore, FIG. 4 and FIG. 6 described above are conceptual cross-sectional views of the sample 12 in which the minute space S is formed in the portion facing the nanowire material 1.

FIG. 7 is a conceptual diagram of one embodiment of an annealing system.
In this embodiment, a sample support 14 is provided in the vacuum chamber 13, and the sample support 14 is provided with a temperature control device (not shown) including temperature measuring means, a control unit, and the like. The sample 12 is supported on the sample support 14 and the vacuum chamber 13 is evacuated. The degree of vacuum of the vacuum chamber 13 does not need to be a high vacuum, and for example, about 10 ⁻⁵ torr is sufficient.

  In this embodiment, a quartz window 13 a is provided on the upper surface of the vacuum chamber 13. An infrared lamp 15 and a condensing mirror 16 are provided on the upper portion of the vacuum chamber 13. The light energy radiated from the infrared lamp 15 is reflected by the condensing mirror 16 and condensed on the sample 12 through the quartz window 13a. The infrared lamp 15 includes a lamp controller 15a, which is controlled in conjunction with the temperature control device of the sample support 14 and controls the temperature and temperature gradient at the sample position.

  The sample 12 is supported on the sample support 14 so that the surface 4b opposite to the surface 4a to which the nanowire material 1 of the substrate 4 is attached is on the infrared lamp 15 side. Thereby, the substrate 4 is annealed by the light energy from the infrared lamp 15 in a state where the temperature is higher than that of the lid member 10 or the covering member 11.

Since Er, which is a nanowire material, easily binds to oxygen, the presence of oxygen has been considered to be an obstacle to the creation of ErSi ₂ nanowires. However, in vacuum, SiO ₂ decomposes at about 1000 ° C. This means that when the substrate 4 is heated to 1000 ° C. or more, even if the surface of the substrate 4 is oxidized, oxygen is liberated and discharged by the vacuum pump. Therefore, the above-described spin coating, laser ablation, or the process of creating a minute space need not be performed in a vacuum, but can be performed in an air atmosphere. On the other hand, ErSi ₂ evaporates at about 1200 ° C. in a vacuum. This means that even if ErSi ₂ nanowires are made, they evaporate at this temperature.
For this reason, the sample 12 is annealed at a temperature of 1000 to 1200 ° C. in a vacuum. The annealing is preferably performed in the range of 1050 to 1150 ° C., more preferably about 1100 ° C. In addition, annealing in this specification means holding a sample at a predetermined temperature.

As shown in FIG. 8, this annealing may be an annealing process in which the temperature is raised to 1000 to 1200 ° C. in one step and the temperature is maintained for a certain period of time, but the material of the nanowire is ErCl ₃ or the like. In the case of a rare earth chloride, as shown in FIG. 9, the temperature is _first raised to the decomposition temperature of the rare earth chloride, for example, about 400 ° C. (T ₁ ), and the temperature is maintained for a certain period of time. A two-stage annealing process in which the temperature is raised to 1200 ° C. (T ₂ ) may be employed. In this case, (t ₁ -t ₀ ) and (t ₃ -t ₂ ) in the figure are temperature rising rates of 100 ° C./sec or more.

In the annealing process, ErSi ₂ nanowires are formed by self-assembly. Although the exact mechanism of nanowire formation by self-organization is unknown, it is thought that it is formed by the following mechanism.

FIG. 10 conceptually shows the mechanism of nanowire formation by self-assembly. ErCl ₃ decomposes into Er and Cl ₂ at about 400 ° C. FIG. 10A schematically shows a state in which Er thus liberated is randomly distributed on the surface 4 a of the Si single crystal substrate 4. When the substrate 4 is annealed while maintaining a constant value in the temperature range of 1000 to 1200 ° C., Er moves on the surface 4a and chemically reacts as schematically shown in FIG. 10B. Then, as shown in FIG. 10C, a certain ordered state is formed by self-organization when the thermodynamic free energy for such a state is more stable than the free energy in the disordered state.

  In the case of the method according to the present invention, since the minute space S is formed facing the surface 4a of the substrate 4, physicochemical equilibrium can be established there, and the above self-organization process can be stably maintained. . If it is a large space rather than a minute space, the physicochemical equilibrium is easily disturbed, and the self-organization process cannot be maintained for a long time. At this time, a part of Er may jump out from the surface of the Si single crystal. However, since it dissipates into a minute space, pressure equilibrium is achieved, and it is possible to prevent the material from evaporating rapidly.

  Further, since the sample 12 is heated by the infrared lamp 15 from the surface 4b side opposite to the surface 4a to which the nanowire material 1 of the substrate 4 is attached, the spacer 9 and the lid member 10 that define the minute space S are heated. Alternatively, the temperature of the covering member 11 is set lower than the temperature of the substrate 4. Thereby, the particles that have jumped out of the substrate 4 tend to be trapped in the spacer 9, the lid member 10, the covering member 11, and the like. That is, only a part can return to the substrate 4, and the nanowire generation process proceeds slowly. As a result, it is considered that the self-organization process can proceed steadily.

FIG. 11 is a low-magnification scanning electron microscope (SEM) image of self-assembled ErSi ₂ nanowires obtained according to the present invention. It can be seen that the length is several micrometers or more. FIG. 12 is a high-magnification scanning electron microscope (SEM) observation image of self-assembled ErSi ₂ nanowires obtained by the present invention. It can be seen that the width is about several nanometers.

FIGS. 13A, 13B, and 13C show ErSi ₂ nanowire atoms formed on the [100], [110], and [111] planes of a Si single crystal according to the present invention, respectively. It is an example of an atomic force microscope (AFM) image. FIG. 14 is an example of an atomic force microscope (AFM) image of a bundle of ErSi ₂ nanowires. It can be seen that a bundle of nanowires is formed in a self-organized manner without following the irregularities of the substrate 4.

FIG. 15 is a conceptual diagram of a unit cell of ErSi ₂ . As can be seen from the figure, it is hexagonal and the spacing between adjacent Er is 0.379 nm. FIG. 16 conceptually shows the structure of the ErSi ₂ nanowire formed on the [001] plane of the Si single crystal. The lattice spacing of the [001] plane of the Si single crystal as the substrate is 0.384 nm. Thus, it is thought that nanowires are formed by the self-assembly process due to the slightly different lattice spacing.

FIG. 17 shows an example in which the length, width, and height of ErSi ₂ nanowires formed on the [110] plane of a Si single crystal according to the present invention are measured as a function of heating temperature. The width and height were nanometer size, and there was no change even when the heating temperature was changed. However, the length increases monotonically from 950 ° C. to 1100 ° C., and gradually decreases after that.

FIG. 18 shows an example in which the length, width, and height of ErSi ₂ nanowires formed on the [110] plane of a Si single crystal according to the present invention are measured as a function of Er concentration. The width and height were nanometer size, and there was no change even when the Er concentration was changed. However, the length increases monotonically with the Er concentration.

FIG. 19 shows an example in which the length, width, and height of ErSi ₂ nanowires formed on the [110] plane of a Si single crystal according to the present invention are measured as a function of heating time. The width and height were nanometer size, and there was no change even when the heating time was changed. However, the length increases monotonously with heating time, and gradually decreases after 9 minutes. This is probably because the nanowires once formed have evaporated again.

Regarding the ErSi ₂ nanowires formed on the [100] surface of the Si single crystal according to the present invention, the same dependency as described above is observed for the heating temperature, Er concentration, and heating time dependency of the length, width, and height. It was done.

  FIG. 20 is an EDS (Energy Dispersive X-ray Spectroscopy) spectrum of a nanowire formed according to the present invention. As can be seen from the figure, peaks corresponding to Si and Er can be seen.

Next, a method for measuring the resistivity of the nanowire will be described. The specific resistivity can be measured using an atomic force microscope.
FIG. 21 is a conceptual diagram of a method for measuring specific resistivity using an atomic force microscope.
A sufficiently large gold electrode 18 is fixed to one end of the nanowire 17, and the gold electrode 18 is grounded. One end of a movable probe 19 is in contact with the nanowire 17 (two probes 19 are drawn in the figure, but actually a single probe is drawn at two positions). . The other end of the probe 19 is connected to the current source A. The current from the current source A flows to the ground point through the probe 19, nanowire 17, and gold electrode 18. Then, the potential difference of the series circuit portion composed of the probe 19 and the nanowire 17 is measured by the voltmeter V. The voltage measured by the voltmeter V is changed by changing the position of the probe. On the other hand, contact resistance or the like is considered not to depend on the position of the probe. Therefore, the specific resistance can be obtained by differentiating the voltage measured by the voltmeter V with the current of the current source.

If the cross-sectional area S and length L of the nanowire are obtained by an atomic force microscope, the specific resistivity ρ can be obtained by the following equation.

ρ = (ΔV / ΔI) (S / L)

  FIG. 22 shows nanowires and gold electrodes on the substrate. Current and voltage were measured at a reference point on the substrate and a measurement point on the nanowire. FIG. 23 shows measured values of current and voltage at the reference points and measurement points in FIG. 22 (the horizontal axis is voltage and the vertical axis is current). From the figure, it can be seen that both are in a linear relationship, and the specific resistivity can be obtained by differentiation.

  FIG. 24 shows multiple measurement points and gold electrodes on the nanowire. The distance, height and width between the plurality of measurement points and the gold electrode were measured, and the current and voltage were measured. FIG. 25 shows the measured values. The horizontal axis is the distance between the measurement point and the gold electrode, the circle is the electrical resistance (left vertical axis), and the square is the corresponding specific resistivity (right vertical axis). It can be seen that the specific resistivity obtained by the differentiation becomes substantially constant, and the specific resistivity as a physical property value is measured.

The specific resistivity of the ErSi ₂ nanowire obtained by the present invention measured by the above method was 6.5 × 10 ⁻⁶ Ωm. On the other hand, the specific resistivity of bulk ErSi ₂ is 1.3 × 10 ⁻⁷ Ωm. The reason why the specific resistivity is higher in the nanowire state in this way can be explained by the fact that the nanowire has a higher probability that electrons are scattered on the surface.

FIG. 26 is a conceptual top view of an electronic device using nanowires as conductive elements according to the present invention. Electrodes are formed on both ends of the nanowire 20 by a known technique such as vapor deposition, and electrodes S and D are formed. In the case of ErSi ₂ nanowires, the surface layer is oxidized to be an insulating layer. An electrode GG is formed so as to cross the nanowire by using, for example, a focused ion beam implantation (FIB) technique. If comprised in this way, it will become an electronic element which uses electrode GG as a control electrode. It is possible to realize a SET (single electron transistor) that controls a single electron by controlling the voltage of the electrode GG.

FIG. 27 is a conceptual top view of an electronic device using two nanowires according to the present invention.
The production method is the same as in FIG. 26, and the electrodes S and D are formed on both ends of the two nanowires 20 and 20, and the electrode R and the electrode W that are in contact with the surface insulating layer of each nanowire are formed using the FIB technology. Etc. are used.

Above, the nanowires of the manufacturing method according to the present invention has been described in detail by way of ErSi ₂ as an example, application of the present invention is not limited thereto. When Si single crystal is used as a substrate, a compound or alloy of rare earth such as Er, Nd, Yb or the like and Si, a 3d transition metal such as Ni, Cr, Co or Mn and a compound or alloy of Si, or an alloy of Ge and Si, etc. It can be applied to the creation of nanowires. In particular, the present invention can be suitably applied when one of the lattice constants of the nanowire is close to one of the lattice constants of the substrate.

FIG. 28 is an example of the NdSi ₂ nanowire generation process according to the present invention observed with an atomic force microscope over time. As can be seen from this observation example, it can be seen that according to the present invention, it is possible to produce nanowires of NdSi ₂ .

It is a conceptual diagram of a spin coating method. It is a conceptual diagram of the laser ablation method. It is a conceptual diagram of the 1st method which makes minute space. It is a conceptual sectional view of a sample which has a minute space created by the 1st method. It is a conceptual diagram of the 2nd method which makes minute space. It is a conceptual sectional view of a sample which has a minute space created by the 2nd method. It is a conceptual diagram of one embodiment of an annealing system. It is the figure which showed an example of the annealing process. It is the figure which showed the other example of the annealing process. It is a conceptual diagram of the mechanism of nanowire formation by self-organization, (A) before annealing, (B) during annealing, (C) shows after annealing. It is an observation image by a low magnification scanning electron microscope (SEM) of a plurality of self-organized ErSi ₂ nanowires. Is an observation image by self-assembled ErSi ₂ nanowires high magnification scanning electron microscope (SEM) in pairs. [100] surface of the Si single crystal, which is an example of a [110] face and [111] between the nanowires of the atomic force ErSi ₂ formed on the surface microscope (AFM) images. ₂ is an example of an atomic force microscope (AFM) image of a bundle of ErSi ₂ nanowires. It is a conceptual diagram of a unit cell of ErSi _2. Si is a diagram conceptually showing the nanowire structure ErSi ₂ formed on the [001] plane of a single crystal. This is an example in which the length, width and height of ErSi ₂ nanowires formed on the [110] plane of a Si single crystal were measured as a function of heating temperature. This is an example in which the length, width and height of ErSi ₂ nanowires formed on the [110] plane of a Si single crystal are measured as a function of Er concentration. This is an example in which the length, width and height of ErSi ₂ nanowires formed on the [110] plane of a Si single crystal were measured as a function of heating time. It is an EDS (energy dispersive X-ray spectroscopy) spectrum of nanowires. It is a conceptual diagram of the method of measuring a specific resistivity using an atomic force microscope. It is a measured value of current and voltage (the horizontal axis is voltage and the vertical axis is current). It is an atomic force microscope (AFM) image (+1,..., +9 is a measurement point) of a nanowire in which electric resistance is measured. It is a measured value of electrical resistance and specific resistivity (the horizontal axis is distance, the left vertical axis is electrical resistance, and the right vertical axis is specific resistivity). It is a notional top view of the electronic device which uses a nanowire as an electroconductive element. It is a notional top view of an electronic device using two nanowires. This is an example in which the generation process of NdSi ₂ nanowires was observed with an atomic force microscope over time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nanowire material 2 Solvent 3 Saturated solution 4 Substrate 4a Crystal surface 4b Back side surface 5 Substrate support stand 6 Target 7 High energy pulse laser beam 8 Evaporated or ionized substance 9 Spacer 9a Hole 10 Lid member 11 Cover member 11a Recess 12 Sample 13 Vacuum chamber 13a Quartz window 14 Sample support 15 Infrared lamp 15a Lamp controller 16 Condensing mirror 17 Nanowire,
18 gold electrode,
19 Movable probe,
20 Nanowire S Micro space A Current source V Voltmeter

Claims (12)

A substrate preparation process for preparing a substrate having a clean crystal surface, a nanowire material preparation process for preparing a nanowire material for forming a nanowire by self-organization on the substrate, and attaching the nanowire material to the surface of the substrate In a nanowire manufacturing method including a material supplying process for causing the substrate to which the material is attached and an annealing process for maintaining the substrate to which the material is attached at a predetermined temperature in a vacuum , a minute space is formed in front of the surface of the substrate to which the nanowire material is attached. A method for producing a nanowire, comprising: forming a minute space to be formed, and performing the annealing process in a state where a minute space is formed in front of the surface of the substrate to which the nanowire material is attached . The nanowire material for forming the nanowire by self-assembly is a rare earth element such as Er, Nd, Yb, or a 3d transition metal element such as Ni, Mn, Cr, Co, or a compound or alloy of Si and Si, or The method for producing a nanowire according to claim 1, wherein the nanowire is Ge or GeEr, or a compound or alloy containing them . 2. The method of manufacturing a nanowire according to claim 1, wherein the surface of the substrate is a [100] plane, a [110] plane, or a [111] plane of a single crystal of Si . The material supply process is a process of applying a solution in which a material for manufacturing the nanowire is dissolved by a spin coating method to the surface of the substrate using a spin coater, or manufacturing the nanowire by a laser ablation method. 2. The method of manufacturing a nanowire according to claim 1, comprising the step of attaching the material to the surface of the substrate by irradiating a laser with the material as a target . In the process of forming the minute space, a spacer provided with a hole is placed in front of the surface of the substrate on which the material is adhered, and the hole of the spacer is covered with a lid member, thereby forming a minute space on the front surface of the substrate. A spacer-type minute space forming process to be formed or a covering member formed with a shallow recess is placed so that the recess is positioned in front of the surface of the substrate to which the material is attached. 2. The method of manufacturing a nanowire according to claim 1, comprising a recess-type microspace forming process for forming a microspace on the front surface . 2. The method of manufacturing a nanowire according to claim 1, wherein in the annealing process, the substrate is heated from a surface side opposite to a surface of the substrate on which the material is adhered . 3. The temperature of the substrate is maintained at a temperature that is higher than an evaporation temperature of a material for forming the nanowire and slightly lower than an evaporation temperature of a constituent element of the nanowire in the annealing process. The manufacturing method of nanowire as described in any one of. 5. The method for producing a nanowire according to claim 4 , wherein the target is ErCl ₃ or Si containing Er . 2. The method of manufacturing a nanowire according to claim 1 , wherein the material of the nanowire is a rare earth chloride such as ErCl ₃ , and the heating temperature of the substrate in the annealing process is 1000 to 1200 ° C. 3. The material of the nanowire is a rare earth chloride such as ErCl ₃ , and the heating temperature of the substrate in the annealing process is in two stages: a decomposition temperature of the rare earth chloride and a wire generation temperature of 1000 to 1200 ° C. The method for producing a nanowire according to claim 1, wherein the method is characterized in that: A method of using nanowires, characterized in that the nanowires formed by the method of claim 1 are used as conductive elements. A nanowire formed by the method is used as a first conductive element, an oxide layer on the surface of the nanowire is used as an electrical insulator element, and a conductive element formed by a known method in the vicinity of the nanowire is used as a second conductive element. An electronic element as an element, wherein the second conductive element is a gate element .

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