JP2022121449A - Production method of compound and production method of graphene nanoribbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably synthesize a graphene nanoribbon having a predetermined length and width.

SOLUTION: A compound represented by general formula (1) is used as a precursor of a graphene nanoribbon. In general formula (1), s is an integer of 1-3, t is an integer of 0-4, and a group X, a group Y, and a group Z are groups in which a bond energy with a carbon atom of an aromatic ring gets larger in the order of a C-X bond, a C-Y bond, and a C-Z bond. By using this compound, a graphene nanoribbon, a joined body of graphene nanoribbons having a semiconductor property and a metal property with widths differing from each other, and a semiconductor device using them are obtained.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a method for producing a compound and a method for producing graphene nanoribbons.

Graphene nanoribbons are known as one of nanocarbon materials. Considering the application of graphene nanoribbons to semiconductor devices, attempts have been made to obtain semiconducting graphene nanoribbons having a bandgap by controlling their width and edge structure. An armchair edge is known as one of the edge structures of graphene nanoribbons. In addition, as one method for obtaining graphene nanoribbons, a bottom-up method (bottom-up synthesis) is known, in which a precursor compound having a molecular structure corresponding to the width is polymerized and cyclized to synthesize graphene nanoribbons. there is

International publication WO2013/061258 pamphlet

Nature, 2010, Vol. 466, p. 470-473

In conventional compounds known as precursors for synthesizing graphene nanoribbons, the atoms released during synthesis terminate the carbon radicals at the starting point of polymer growth, inhibiting polymer growth, i.e., polymerization. There is Once the polymerization is inhibited in this way, it is possible to stably synthesize graphene nanoribbons of a given width with sufficient length, for example, graphene nanoribbons with a length and width that can be applied to semiconductor devices. becomes difficult.

One aspect of the present invention provides a compound represented by the following general formula (1).

[In the general formula (1), s is an integer of 1 to 3, t is an integer of 0 to 4, and the X group, the Y group, and the Z group have a bond energy with the carbon atom of the aromatic ring that is C- It is a group that becomes larger in the order of X bond, CY bond, and CZ bond. ]
Moreover, according to one aspect, there are provided a method for producing the compound as described above and a method for producing graphene nanoribbons using the compound as described above.

According to one aspect, a semiconducting first graphene nanoribbon having a first width, and a metallic graphene nanoribbon having a second width larger than the first width joined to one end in the length direction of the first graphene nanoribbon and a second graphene nanoribbon of .

Moreover, according to one aspect, a semiconductor device using the above graphene nanoribbons is provided.

It is possible to control the polymerization of compounds and stably synthesize graphene nanoribbons having a predetermined length and width. Moreover, it becomes possible to realize a high-performance semiconductor device using such graphene nanoribbons.

FIG. 5 is an explanatory diagram of a precursor and AGNR synthesis using the same according to a second embodiment; FIG. 10 is an explanatory diagram of precursor synthesis according to the second embodiment; FIG. 11 is an explanatory diagram of AGNR junction synthesis according to the second embodiment; FIG. 11 is an explanatory diagram of a ribbon length of AGNR according to the second embodiment; FIG. 11 is an explanatory diagram of a ribbon width of AGNR according to the second embodiment; FIG. 10 is an explanatory diagram of a planar shape of an AGNR junction according to the second embodiment; FIG. 10 is an explanatory diagram of a precursor according to a third embodiment and AGNR synthesis using the same; FIG. 11 is an explanatory diagram of AGNR junction synthesis according to the third embodiment; FIG. 10 is an explanatory diagram of a precursor according to a fourth embodiment and AGNR synthesis using the same; FIG. 11 is an explanatory diagram of AGNR junction synthesis according to the fourth embodiment; FIG. 14 is an explanatory diagram (part 1) of the method for manufacturing the semiconductor device according to the fifth embodiment; FIG. 22 is an explanatory diagram (part 2) of the method for manufacturing the semiconductor device according to the fifth embodiment; FIG. 21 is an explanatory diagram (part 3) of the manufacturing method of the semiconductor device according to the fifth embodiment; FIG. 21 is an explanatory diagram (part 4) of the manufacturing method of the semiconductor device according to the fifth embodiment; FIG. 20 is an explanatory diagram (No. 5) of the manufacturing method of the semiconductor device according to the fifth embodiment; FIG. 20 is an explanatory diagram (No. 6) of the method for manufacturing the semiconductor device according to the fifth embodiment; It is a figure which shows the 1st example of the semiconductor device which concerns on 6th Embodiment. FIG. 11 is a diagram showing a second example of a semiconductor device according to a sixth embodiment; It is a figure which shows the 3rd example of the semiconductor device which concerns on 6th Embodiment. It is a figure explaining an electronic device.

First, graphene and graphene nanoribbons are described.
Graphene is a material with a sheet structure in which six-membered rings of carbon (C) atoms are laid out in a two-dimensional plane. Graphene has extremely high carrier (electron and hole) mobility even at room temperature and exhibits unique electronic properties such as ballistic conduction and half-integer quantum Hall effect. Research and development of nanoelectronic devices that take advantage of such properties of graphene have been actively carried out in recent years.

Since the conjugation of π electrons extends two-dimensionally, graphene has a bandgap equal to zero and exhibits metallic properties (gapless semiconductor). However, when the size of graphene becomes nanoscale, the number of C atoms in the bulk forming the sheet structure and the number of C atoms forming the edges become equal, and the shape and edges strongly affect the graphene. It comes to show different physical properties.

As nano-sized graphene, quasi-one-dimensional graphene in a ribbon shape with a width of several nm, so-called graphene nanoribbon (GNR), is widely known. The physical properties of GNR vary greatly depending on the edge structure and ribbon width.

There are two types of edge structures of GNRs: an armchair edge in which C atoms are arranged in a two-atom cycle, and a zigzag edge in which C atoms are arranged in a zigzag pattern. Armchair-edge GNRs (AGNRs) exhibit semiconducting properties due to the opening of a finite bandgap due to quantum confinement and edge effects. On the other hand, the zigzag-edged GNR (ZGNR) exhibits magnetic or metallic properties.

AGNR is referred to as N-AGNR by the number N of CC dimer lines counted across the width of the ribbon. For example, AGNR whose basic unit is anthracene, in which three six-membered rings are arranged in the width direction of the AGNR ribbon, is called 7-AGNR. Further, according to the value of N, they are classified into three subgroups of N=3p, 3p+1, 3p+2 (p is a positive integer). From first-principles calculations considering many-body effects (for example, Physical Review Letters, 2007, Vol. 99, p.186801-1-4), N-AGNR within the same subgroup The magnitude of the bandgap Eg of is known to decrease with increasing values of N, ie the ribbon width. Also, the bandgaps Eg3p, Eg3p+1, and Eg3p+2 among the subgroups have a magnitude relationship of Eg3p+1>Eg3p>Eg3p+2.

As a technique for forming GNR, a top-down method of cutting a graphene sheet by electron beam lithography and etching (for example, Physical Review Letters, 2007, Vol. 98, p.206805-1~ 4), a method of chemically dissecting carbon nanotubes (for example, Nature, 2009, Vol. 458, p.872-876), a method of forming from graphite flakes dissolved in an organic solvent by a sonochemical method ( For example, Science, 2008, Vol. 319, p.1229-1232) and the like have been reported. Controlling the ribbon width and edge structure is important for forming GNRs that exhibit stable physical properties. There is a concern that In addition, the above method has the problem that it is not easy to uniform the width of the ribbon, and it is difficult to obtain a GNR exhibiting stable physical properties.

On the other hand, as a technique for forming GNR, a technique for forming AGNR in a bottom-up manner has been reported (for example, Non-Patent Document 1 above). In this method, a precursor formed in advance by organic chemical synthesis is vapor-deposited on a predetermined substrate under an ultra-high vacuum, and the precursors are polymerized and cyclized on the substrate by heating to synthesize AGNR ( bottom-up synthesis). For example, 10,10′-dibromo-9,9′-bianthracene is used as a precursor (monomer), which is vapor-deposited on a predetermined substrate and heated at 200° C., bromine (Br) atoms are desorbed, and the precursor A polymer chain is formed in which the bodies are polymerized at their centers. Furthermore, when heated at 400° C., hydrogen (H) atoms are eliminated and a cyclization reaction is induced to form semiconducting 7-AGNR with a bandgap Eg of 3.8 eV. Such bottom-up synthesis is considered effective for forming GNRs exhibiting stable physical properties.

However, in the bottom-up synthesis, when a molecule in which the aromatic ring is terminated with an H atom is used as the precursor, the H atom eliminated by the partial cyclization reaction is replaced by the Br atom even when heated at a relatively low temperature. It may terminate separated C radicals (C—H bonds or C—H ₂ bonds) and inhibit polymerization. Such suppression of polymerization is a factor that hinders the increase in the ribbon length of AGNR, and for example, the average ribbon length of synthesized AGNR is limited to about 30 nm. In addition, the shorter the polymer chain, the more thermally diffused on the substrate. bodies, so-called AGNR junctions, are likely to be formed.

From the viewpoint of application of AGNR to electronic devices, conventional ribbon lengths may not be sufficient. For example, when AGNR is used for the channel of a transistor, realization of AGNR with a ribbon length of several hundred nm is expected in order to simplify the manufacturing process and reduce the contact resistance with the electrode.

In view of the above points, here, a method for obtaining AGNR by bottom-up synthesis using compounds as precursors as described in the following embodiments will be described.
First, a first embodiment will be described.

A compound used as a precursor of AGNR has a structure as shown in formula (2).

In formula (2), s is an integer of 1 to 3, t is an integer of 0 to 4, and the X group, Y group and Z group have a bond energy with the C atom of the aromatic ring that is a C—X bond, It is a group that becomes larger in the order of CY bond and CZ bond. In other words, the X group, Y group and Z group can be said to be groups in which the elimination temperature from the aromatic ring increases in the order of X, Y and Z.

Thus, the compound of formula (2) has an aromatic ring (benzene or acene or a dimer thereof) such as benzene, anthracene, pentacene, heptacene, or nonacene, to which an X group, a Y group, or a Z group is attached, thereby forming an aromatic ring. has a structure in which the C atoms of are terminated.

X group, Y group and Z group are, for example, independently of each other halogen atoms such as fluorine (F) atom, chlorine (Cl) atom, Br atom and iodine (I) atom. In the compound represented by formula (2), the halogen atoms are bonded in a combination such that the bond energy with the C atom of the aromatic ring increases in the order of C—X bond, C—Y bond, and C—Z bond. . For example, a combination of X=I, Y=Br and Z=Cl and a combination of X=Br, Y=Cl and Z=F are bonded to the C atoms of the aromatic ring. In this way, when the X group, the Y group and the Z group are halogen atoms, the bond energy with the C atom of the aromatic ring increases in the order of the C—X bond, the CY bond, and the C—Z bond. It can also be said that the atomic weight decreases in the order of the X group, the Y group, and the Z group.

X group, Y group and Z group are halogen atoms as described above, provided that the bond energy with the C atom of the aromatic ring increases in the order of C—X bond, C—Y bond, and C—Z bond. is not limited to For example, the groups X, Y and Z independently of each other can be nitrile groups (CN groups), nitro groups (NO ₂ groups), trihalogenated methyl groups (CF ₃ groups, CCl ₃ groups, CBr ₃ groups , CI ₃ groups).

The compound of formula (2) has a structure in which the C atoms of the aromatic ring are not terminated with H atoms, ie, the structure does not contain a C—H bond.
A precursor as represented by the formula (2) is synthesized as follows.

First, a compound represented by the formula (3), that is, a compound having a structure in which an H atom is bonded to the X group of the above formula (2) and an amino group (NH ₂ group) is bonded to the Y group, is prepared.

The _NH2 group of the prepared compound of formula (3) is converted to a Y group to give compounds as shown in formula (4).

The H atom of the resulting compound of formula (4) is converted to an X group to give the compound of formula (2) above.
In formulas (3) and (4), s is an integer of 1 to 3, t is an integer of 0 to 4, and the X group, Y group and Z group have binding energy with the C atom of the aromatic ring , C—X bond, CY bond, and C—Z bond.

For example, as the compound of formula (2), 1,4,5,8-tetrabromo-2,3,6,7-tetrachloro-9,10-diiodoanthracene (s=t=1, X=I, Y=Br, Z=Cl) can be synthesized as follows. First, prepare 1,4,5,8-tetraamino-2,3,6,7-tetrachloroanthracene (1,4,5,8-tetraamino-2,3,6,7-tetrachloroanthracene), The _NH2 group is converted to a Br group by the Sandmeyer reaction or the like to give 1,4,5,8-tetrabromo-2,3,6,7-tetrachloroanthracene (1,4,5,8-tetrabromo-2, 3,6,7-tetrachloroanthracene). Group I is then introduced by an iodination reaction to give 1,4,5,8-tetrabromo-2,3,6,7-tetrachloro-9,10-diiodoanthracene (1,4,5,8-tetrabromo -2,3,6,7-tetrachloro-9,10-diiodoanthracene).

Various precursors as represented by the above formula (2) can be obtained according to examples of such methods.
Next, synthesis of AGNR using the precursors as described above will be described.

In synthesizing AGNR, first, a precursor represented by the above formula (2) is vapor-deposited (vacuum vapor-deposited) on a heated substrate such as the (111) plane of gold (Au) in a vacuum. During this vacuum deposition, the precursor group deposited on the substrate is polymerized to synthesize a polymer chain of an aromatic compound as shown in formula (5).

In the precursor of formula (2) above, the bond energy of the C—X bond is lower than that of the CY bond and the C—Z bond. During vacuum deposition, heating is performed at a temperature at which the X group is eliminated and at a temperature at which the elimination of the Y and Z groups is suppressed. When vacuum deposition is performed at such a temperature, the X group is preferentially eliminated compared to the elimination of the Y and Z groups, and the elimination of the X group and the bond between the C atoms ( C—C bond) reaction is induced to stably synthesize a polymer chain (degree of polymerization n) of formula (5) polymerized at the linking point in the middle of the molecule. Since the elimination of the Y group and the Z group is suppressed compared to the elimination of the X group, bonding between the precursor and the polymer chain or between the polymer chains other than the central linking point is suppressed.

The synthesized polymer chain is further heated in vacuum at a higher temperature (first high-temperature heating). During this first high-temperature heating, cyclization proceeds in the polymer chains on the substrate to synthesize AGNR as shown in formula (6).

In the polymer chain of formula (5), the bond energy of the CY bond is lower than that of the CZ bond. During the first high-temperature heating, heating is performed at a temperature at which the Y group is detached and at a temperature at which the detachment of the Z group is suppressed. When the first high-temperature heating is performed at such a temperature, the Y group preferentially eliminates compared to the Z group, and the elimination of the Y group and the C—C bond reaction are induced to promote cyclization, and the formula ( AGNR such as 6) is stably synthesized. Since elimination of the Z group is suppressed more than elimination of the Y group, bonding between polymer chains, between a polymer chain and AGNR, or between AGNRs in the width direction (ribbon width direction) is suppressed.

In the precursor of formula (2) above, and the polymer chain of formula (5) and AGNR of formula (6) synthesized using it, the C atom of the aromatic ring is not terminated with an H atom. Therefore, in the process of synthesizing the polymer chain of formula (5) by vacuum vapor deposition and the process of synthesizing AGNR of formula (6) by the first high-temperature heating, the desorption of H atoms and the generation of C radicals due to this is suppressed. As a result, in the process of synthesizing the polymer chain of the formula (5), termination of polymerization due to detached H atoms is suppressed, and the degree of polymerization n is increased, that is, the ribbon length of the finally obtained AGNR is increased. can be done. For example, AGNRs with ribbon lengths of several hundred nm are realized. In the process of synthesizing the polymer chain of formula (5) and the process of synthesizing AGNR of formula (6), random It is possible to suppress unintentional bonding and bonding at points other than the intended bonding points.

The AGNR of formula (6) synthesized as described above may be further heated in a vacuum at a higher temperature (second high-temperature heating). During the second high-temperature heating, heating is performed at a temperature at which the Z group is eliminated. When the second high-temperature heating is performed at such a temperature, elimination of the Z group and CC bond reaction are induced between the AGNRs adjacent in parallel. As a result, an AGNR junction is synthesized in which AGNRs are six-membered ring-joined in the width direction of the ribbon. In the AGNR of formula (6), since the C atom of the aromatic ring is not terminated with an H atom, the elimination of the H atom and the resulting generation of C radicals are suppressed, and defects such as 5- and 7-membered rings are suppressed. It is possible to synthesize an AGNR junction in which the occurrence of is suppressed.

By using the precursor of the above formula (2) and utilizing the difference in binding energy between the C atom of the aromatic ring and the difference in desorption temperature between the X group, the Y group and the Z group, and performing the synthesis as described above. , AGNR and AGNR junctions with long ribbon length and reduced defects can be synthesized.

Examples of the above precursors and AGNRs and AGNR junctions synthesized using the precursors will be described below as second to fourth embodiments.
First, a second embodiment will be described.

FIG. 1 is an explanatory diagram of a precursor and AGNR synthesis using the precursor according to the second embodiment. FIG. 2 is an explanatory diagram of precursor synthesis according to the second embodiment.
In this example, the precursor 10a as shown in FIG. 1 is used, namely 1,4,5,8-tetrabromo-2,3,6,7-tetrachloro-9,10-diiodoanthracene. This precursor 10a is a molecule having a structure in which s=t=1, X=I, Y=Br, and Z=Cl in the above formula (2).

The precursor 10a is synthesized, for example, as shown in FIG. First, 1,4,5,8-tetraamino-2,3,6,7-tetrachloroanthracene (compound 11 in FIG. 2) was prepared and its _NH2 groups were converted to Br groups by Sandmeyer reaction. , 1,4,5,8-tetrabromo-2,3,6,7-tetrachloroanthracene (compound 12 in FIG. 2) is obtained. Group I is then introduced by an iodination reaction, 1,4,5,8-tetrabromo-2,3,6,7-tetrachloro-9,10-diiodoanthracene (compound 13 in FIG. 2, A precursor 10a) is obtained.

A precursor 10a as shown in FIG. 1 (and FIG. 2) is vacuum-deposited on a predetermined substrate and further heated to synthesize 7-AGNR30a.
Here, for example, a single-crystal metal substrate is used as the substrate on which the precursor 10a is vacuum-deposited. As such a single crystal metal substrate, for example, an Au (111) plane is used. As a single crystal metal substrate, in addition to Au (111) surface, copper (Cu), nickel (Ni), rhodium (Rh), palladium (Pd), silver (Ag), iridium (Ir), platinum (Pt), etc. The (111) plane of may be used. Also, in order to control the directivity of the synthesized AGNR, a single-crystal metal miscut substrate as described above, which has a periodic structure of steps and terraces several nm wide, may be used. Alternatively, in addition to metallic crystal substrates, semiconducting crystal substrates such as IV group semiconductors, III-V group compound semiconductors, II-VI group compound semiconductors, and transition metal oxide semiconductors may be used. Here, the Au (111) plane will be described as an example.

As a pretreatment for vapor deposition of the precursor 10a, argon (Ar) ion sputtering and ultra-high vacuum are performed for the purpose of removing organic impurities (contamination) on the Au (111) surface and improving the flatness of the Au (111) surface. A plurality of cycles of surface cleaning treatment with annealing as one set are performed. In the surface cleaning treatment per set, Ar ion sputtering was performed for 1 minute at an ion acceleration voltage of 0.8 kV to 2.0 kV and an ion current of 1.0 μA to 10.0 μA, and ultra-high vacuum annealing was performed at 5×10 ⁻ It is carried out at 300° C. to 450° C. for 10 minutes while maintaining a degree of vacuum of ⁷ Pa or less. For example, such surface cleaning treatment is performed for three cycles.

7-AGNR is synthesized in-situ on the Au(111) surface in an ultra-high vacuum chamber without exposing the surface-cleaned Au(111) surface to the atmosphere.
At that time, first, the precursor 10a is sublimated by heating to 100 ° C. to 150 ° C. with a K-cell type evaporator under an ultra-high vacuum with a basic degree of vacuum of 5 × 10 ^-8 Pa or less. It is deposited on the Au(111) surface held at ~150°C. The deposition rate is set to, for example, 0.05 nm/min to 0.1 nm/min. The deposited film thickness is set to, for example, 0.5 ML to 1 ML (ML: monolayer, 1 ML is approximately 0.2 nm).

In the precursor 10a, among the CI bond, the C-Br bond, and the C-Cl bond in which the I atom, the Br atom, and the Cl atom are bonded to the anthracene of the basic skeleton, the C-I The bond energy of the bond is lower than those of other C--Br bonds and C--Cl bonds. In the precursor 10a deposited on the Au (111) surface at 100° C. to 150° C., the I atom is desorbed (de-I) by breaking the C—I bond, while the C—Br bond and the C— Detachment of Br atoms and Cl atoms due to breaking of Cl bonds is suppressed. On the Au(111) surface at 100° C.-150° C., de-Iylation and C—C bond reactions between the de-Iylated C atoms were induced and polymerized at the central linking point of the precursor 10a molecule. A polymer chain 20a as shown in FIG. 1 is stably synthesized.

In the process of synthesizing the polymer chain 20a, the C atoms other than the linking point at the center of the molecule of the precursor 10a are bound to Br and Cl atoms having higher binding energy than the I atom. On the Au(111) plane, desorption of Br and Cl atoms is suppressed. Therefore, bonding between the precursor 10a and the polymer chain 20a or between the polymer chains 20a on the Au (111) surface at 100° C. to 150° C. is suppressed except for the central connecting point.

The basic skeleton of the precursor 10a does not contain a C—H bond, and the elimination of H atoms and the resulting generation of C radicals are suppressed in the process of synthesizing the polymer chain 20a. Therefore, the polymer chain 20a is effectively stretched in the length direction (the ribbon length direction P of the 7-AGNR 30a to be synthesized). The length of the polymer chain 20a (and the length of the ribbon of the synthesized 7-AGNR 30a) is controlled by, for example, the planar shape (its length) of the underlying substrate such as the Au (111) plane.

Following vacuum deposition to synthesize the polymer chains 20a as described above, the Au(111) surface is heated to 200° C.-250° C. at a heating rate of, for example, 1° C./min to 5° C./min. Holds from minutes to 1 hour. In the polymer chain 20a synthesized on the Au (111) surface at 200° C. to 250° C., the Br atom is eliminated (de-Br) due to the breaking of the C—Br bond, while the C—Cl bond is broken. detachment of Cl atoms by is suppressed. On the Au(111) surface at 200° C. to 250° C., deBrization and C—C bond reactions between the deBrized C atoms are induced, and cyclization of the polymer chain 20a proceeds. As a result, as shown in FIG. 1, 7-AGNR30a having a width corresponding to seven C atoms in the ribbon width direction Q and having edges terminated with Cl atoms is stably synthesized.

In the process of synthesizing 7-AGNR30a, as described above, on the Au (111) surface at 200° C. to 250° C., desorption of Cl atoms is suppressed. Therefore, random bonding between polymer chains 20a, between polymer chains 20a and 7-AGNR30a, or between 7-AGNR30a on the Au (111) plane at 200 ° C. to 250 ° C., bonding other than the intended bonding point ( bonding in the ribbon width direction Q) is suppressed.

Thus, in the synthesis of 7-AGNR30a using the precursor 10a, the desorption temperature difference between the I, Br, and Cl atoms bonded to the anthracene in the basic skeleton of the precursor 10a is utilized. That is, first, the elimination of the I atom, which has the lowest elimination temperature, and the C—C bond reaction are induced by heating at a predetermined temperature to synthesize the polymer chain 20a elongated in the length direction. Then, the elimination of the Br atom whose elimination temperature is intermediate and the C—C bond reaction are induced by heating at a higher temperature, the polymer chain 20a is cyclized, and 7-AGNR30a is synthesized. As a result, 7-AGNR30a having a long ribbon length and suppressed occurrence of defects is stably synthesized.

Following the heating for synthesizing 7-AGNR30a as described above, when the Au (111) plane is further heated at a high temperature, if the 7-AGNR30a group adjacent to the ribbon width direction Q exists on the Au (111) plane, they can be joined in the ribbon width direction Q.

FIG. 3 is an explanatory diagram of AGNR junction synthesis according to the second embodiment.
For example, following heating to synthesize 7-AGNR30a, the Au(111) surface is heated to 300° C. to 350° C. and held for 10 minutes to 1 hour. In the 7-AGNR30a synthesized on the Au (111) surface at 300° C. to 350° C., the Cl atom is eliminated (de-Cl) due to the breaking of the C—Cl bond. On the Au (111) plane at 300 ° C. to 350 ° C., when the 7-AGNRs 30a extending parallel to the ribbon length direction P (7-AGNRs 31a and 32a in FIG. 3) are adjacent to each other in the ribbon width direction Q, , deCl, and C—C bond reactions between the deClized C atoms are induced. As a result, an AGNR (7-AGNR junction) 40a is synthesized in which the 7-AGNRs 30a are six-membered ring-joined in the ribbon width direction Q. Here, as an example, a planar L-shaped 7-AGNR junction 40a is illustrated. The planar shape of the 7-AGNR junction 40a is controlled by, for example, the planar shape of the underlying substrate such as the Au (111) plane.

Here, the planar shapes of the 7-AGNR 30a and the 7-AGNR junction 40a will be described with reference to FIGS. 4 to 7. FIG.
FIG. 4 is an explanatory diagram of the ribbon length of AGNR according to the second embodiment. FIGS. 4A to 4C schematically show plan views of the AGNR and its underlying substrate, respectively.

For example, as shown in FIG. 4A, on a substrate 50 such as an Au (111) surface having a predetermined length in the ribbon length direction P of the 7-AGNR 30a to be synthesized, 7 -AGNR30a is synthesized. 7-AGNR 30a is synthesized on the substrate 50 with a ribbon length corresponding to its length. If the length of this substrate 50 is made longer than in the case of FIG. 4A, as shown in FIG. 4B, 7-AGNR 30a longer than that in FIG. is synthesized. Similarly, if the length of the substrate 50 is made longer than in FIG. 4B, as shown in FIG. A long 7-AGNR30a is synthesized.

Thus, 7-AGNR 30a can be synthesized with a ribbon length that depends on the length of the substrate 50 on which it is synthesized. In the synthesis of 7-AGNR30a, precursor 10a as described above was used, and the synthesis (and cyclization) of polymer chain 20a was performed above the elimination temperature of the I atom and above the elimination temperature of the Br and Cl atoms. By carrying out at a low temperature, the polymerization of the precursor 10a can be continued for a length corresponding to the length of the substrate 50. FIG. Therefore, it is possible to synthesize the polymer chain 20a with a degree of polymerization n corresponding to the length of the substrate 50, and cyclize the synthesized polymer chain 20a to form 7-AGNR30a having a ribbon length corresponding to the length of the substrate 50. Can be synthesized. In other words, the length of the substrate 50 can control the ribbon length of the 7-AGNR 30a.

FIG. 5 is an explanatory diagram of the ribbon width of the AGNR according to the second embodiment. 5A to 5C schematically show plan views of the AGNR and its underlying substrate, respectively.

For example, as shown in FIG. 5A, a substrate 50 such as an Au (111) surface having a predetermined width in the ribbon width direction Q of the 7-AGNR 30a to be synthesized is coated with 7- AGNR30a is synthesized. 7-AGNR 30a is synthesized on the substrate 50 according to its width. For the sake of convenience, FIG. 5A exemplifies the case where one 7-AGNR 30a is synthesized on the substrate 50. As shown in FIG. As shown in FIG. 5B, if the width of this substrate 50 is made wider than in the case of FIG. A wider AGNR than in FIG. 5A, namely a 7-AGNR junction 40a is synthesized. For the sake of convenience, FIG. 5B exemplifies a case where two 7-AGNRs 30a are joined to synthesize a 7-AGNR junction 40a. Similarly, if the width of the substrate 50 is made wider than in the case of FIG. 5B, as shown in FIG. An even wider 7-AGNR junction 40a is synthesized. For the sake of convenience, FIG. 5(C) illustrates a case where three 7-AGNRs 30a are joined to synthesize a 7-AGNR junction 40a.

Thus, the 7-AGNR junction 40a can be synthesized with a width that corresponds to the width of the substrate 50 on which the 7-AGNR 30a is synthesized. In the synthesis of 7-AGNR30a, the precursor 10a as described above is used, and the synthesis and cyclization of the polymer chain 20a are performed at a temperature lower than the desorption temperature of the Cl atom, thereby forming random bonds in the ribbon width direction Q Also, the synthesis can be performed while suppressing the occurrence of defects. Therefore, it is possible to synthesize 7-AGNR 30a with an arrangement number corresponding to the width of the substrate 50, and by heating at a temperature higher than the desorption temperature of Cl atoms, 7-AGNR junctions having a width corresponding to the width of the substrate 50 40a can be synthesized. In other words, the width of the substrate 50 can control the width of the 7-AGNR junction 40a.

In addition, since the width of the 7-AGNR junction 40a is controlled by the width of the substrate 50 in this manner, the semiconductor 7-AGNR junction 40a and the metallic 7-AGNR junction 40a can be separately produced depending on the width of the substrate 50. can be done.

FIG. 6 is an explanatory diagram of the planar shape of the AGNR junction according to the second embodiment. FIGS. 6A to 6C schematically show plan views of the AGNR and its underlying substrate, respectively.

As described above, the 7-AGNR 30a and the 7-AGNR junction 40a can be synthesized with a planar shape (length and width) corresponding to the planar shape (length and width) of the substrate 50 on which they are synthesized. For example, if a planar L-shaped substrate 50 as shown in FIG. 6A is used, a planar L-shaped 7-AGNR junction 40a can be synthesized thereon. For example, if a planar T-shaped substrate 50 as shown in FIG. 6B is used, a planar T-shaped 7-AGNR junction 40a can be synthesized thereon. For example, if a planar I-shaped substrate 50 as shown in FIG. 6C is used, a planar I-shaped 7-AGNR junction 40a can be synthesized thereon. By selecting the planar shape of the substrate 50, the 7-AGNR junction 40a with various planar shapes can be synthesized thereon.

In addition, since the planar shape of the 7-AGNR junction 40a is controlled by the planar shape of the substrate 50 in this way, the planar shape of the substrate 50 includes narrow and wide portions or semiconducting and metallic portions. The 7-AGNR junction 40a can be synthesized.

Next, a third embodiment will be described.
FIG. 7 is an explanatory diagram of a precursor and AGNR synthesis using the precursor according to the third embodiment.
In this example, the precursor 10b as shown in FIG. 6',7,7'-octafluoro-10,10'-dibromo-9,9'-bianthryl (1,1',4,4',5,5',8,8'-octachloro-2,2 ',3,3',6,6',7,7'-octafluoro-10,10'-dibromo-9,9'-bianthryl) is used. This precursor 10b is a molecule having a structure in which s=2, t=1, X=Br, Y=Cl, and Z=F in the above formula (2).

A precursor 10b as shown in FIG. 7 is vacuum-deposited on a predetermined substrate and further heated to synthesize 7-AGNR30b.
For example, the precursor 10b is vapor-deposited on the Au (111) surface that has been subjected to the surface cleaning treatment in the same manner as described in the second embodiment. Since the precursor 10b has a larger number of benzene rings and a higher molecular weight than the precursor 10a (FIG. 1), its sublimation temperature is higher. The precursor 10b is heated to 200.degree. C. to 250.degree.

In the precursor 10b, among the C—Br bonds, C—Cl bonds, and CF bonds in which Br atoms, Cl atoms, and F atoms are bonded to the basic skeleton of bianthryl, C—Br, which serves as a linking point between the precursors 10b The bond energy of the bond is lower than those of other C--Cl bonds and CF bonds. In the precursor 10b deposited on the Au(111) surface at 200° C. to 250° C., Br atoms are detached by breaking the C—Br bond, while the C—Cl and C—F bonds are broken. Detachment of Cl atoms and F atoms by is suppressed. On the Au(111) surface at 200° C. to 250° C., deBr and C—C bond reactions are induced to form polymer chains 20b as shown in FIG. Synthesized stably. On the Au (111) surface at 200° C. to 250° C., the elimination of Cl atoms and F atoms is suppressed, and the bonding between the precursor 10b and the polymer chain 20b, or between the polymer chains 20b other than at the central connection point is suppressed.

The basic skeleton of the precursor 10b does not contain a C—H bond, and in the process of synthesizing the polymer chain 20b, the elimination of H atoms and the resulting generation of C radicals are suppressed. The 7-AGNR30b to be synthesized is effectively stretched in the ribbon length direction P). The length of the polymer chain 20b (and the length of the ribbon of 7-AGNR30b to be synthesized) is controlled, for example, by the planar shape (its length) of the underlying substrate such as the Au (111) plane.

Following vacuum deposition to synthesize the polymer chain 20b as described above, the Au(111) surface is heated to 300° C.-350° C. at a heating rate of, for example, 1° C./min to 5° C./min. Holds from minutes to 1 hour. In the polymer chain 20b synthesized on the Au (111) surface at 300° C. to 350° C., the Cl atom is eliminated by breaking the C—Cl bond, while the F atom is eliminated by breaking the C—F bond. separation is suppressed. On the Au(111) surface at 300° C. to 350° C., deClification and C—C bond reactions are induced, and cyclization of the polymer chain 20b proceeds. As a result, 7-AGNR30b whose edges are terminated with F atoms, as shown in FIG. 7, is stably synthesized. On the Au (111) surface at 300 ° C. to 350 ° C., the elimination of F atoms is suppressed, and random bonding between polymer chains 20b, between polymer chains 20b and 7-AGNR30b, or between 7-AGNR30b. Bonding (bonding in the ribbon width direction Q) at points other than bonding points is suppressed.

As described in the second embodiment (FIG. 4), 7-AGNR30b synthesized using the precursor 10b is a ribbon depending on the length of the underlying substrate such as the Au (111) plane. synthesized in length.

Thus, in the synthesis of 7-AGNR30b using the precursor 10b, the desorption temperature difference between the Br, Cl and F atoms bonded to the bianthryl of the basic skeleton of the precursor 10b is utilized. That is, first, desorption of the Br atom having the lowest desorption temperature and C—C bond reaction are induced by heating at a predetermined temperature to synthesize the polymer chain 20b elongated in the length direction. Then, the elimination of the Cl atom with the intermediate elimination temperature and the C—C bond reaction are induced by heating at a higher temperature, the polymer chain 20b is cyclized, and 7-AGNR30b is synthesized. As a result, 7-AGNR30b having a long ribbon length and suppressed occurrence of defects is stably synthesized.

Following the heating for synthesizing 7-AGNR30b as described above, when the Au (111) plane is further heated at a high temperature, if the 7-AGNR30b group adjacent to the ribbon width direction Q exists on the Au (111) plane, they can be joined in the ribbon width direction Q.

FIG. 8 is an explanatory diagram of AGNR junction synthesis according to the third embodiment.
For example, following heating to synthesize 7-AGNR30b, the Au(111) surface is heated to 400° C. to 450° C. and held for 10 minutes to 1 hour. In the 7-AGNR30b synthesized on the Au (111) surface at 400° C. to 450° C., the F atom is eliminated (de-F) by breaking the C—F bond. On the Au (111) plane at 400 ° C. to 450 ° C., when the 7-AGNRs 30b extending parallel to the ribbon length direction P (7-AGNRs 31b and 32b in FIG. 8) are adjacent to each other in the ribbon width direction Q, , de-Fated, and C—C bond reactions between de-Fated C atoms are induced. As a result, an AGNR (7-AGNR junction) 40b is synthesized in which 7-AGNR 30b are six-membered ring-joined in the width direction Q of the ribbon. Here, as an example, a planar L-shaped 7-AGNR junction 40b is illustrated.

As described in the second embodiment (FIGS. 5 and 6), the 7-AGNR junction 40b is synthesized with a planar shape corresponding to the planar shape of the underlying substrate such as the Au (111) plane. be.

Next, a fourth embodiment will be described.
FIG. 9 is an explanatory diagram of a precursor and AGNR synthesis using the precursor according to the fourth embodiment.
In this example, the precursor 10c as shown in FIG. Pentacene (1,4,5,7,8,11,12,14-octachloro-2,3,9,10-tetrafluoro-6,13-dibromopentacene) is used. This precursor 10c is a molecule having a structure in which s=1, t=2, X=Br, Y=Cl, and Z=F in the above formula (2).

A precursor 10c as shown in FIG. 9 is vacuum-deposited on a predetermined substrate and further heated to synthesize 11-AGNR30c having a width corresponding to 11 C atoms in the ribbon width direction Q. be.

For example, the precursor 10c is vapor-deposited on the Au (111) surface that has undergone surface cleaning treatment in the same manner as described in the second embodiment. The precursor 10c is sublimated by heating to 200.degree. C. to 250.degree.

In the precursor 10c, among the C—Br bonds, C—Cl bonds, and CF bonds in which Br atoms, Cl atoms, and F atoms are bonded to the pentacene of the basic skeleton, C—Br, which serves as a connecting point between the precursors 10c The bond energy of the bond is lower than those of other C--Cl bonds and CF bonds. In the precursor 10c deposited on the Au(111) surface at 200° C. to 250° C., the C—Cl and C—F Detachment of Cl atoms and F atoms by is suppressed. On the Au(111) surface at 200° C. to 250° C., deBr and C—C bond reactions are induced to form polymer chains 20c as shown in FIG. Synthesized stably. On the Au (111) surface at 200° C. to 250° C., the elimination of Cl atoms and F atoms is suppressed, and the bonding between the precursor 10c and the polymer chain 20c or between the polymer chains 20c other than at the central connection point is suppressed.

The basic skeleton of the precursor 10c does not contain a C—H bond, and in the process of synthesizing the polymer chain 20c, the elimination of H atoms and the resulting generation of C radicals are suppressed. The 11-AGNR30c to be synthesized is effectively stretched in the ribbon length direction P). The length of the polymer chain 20c (and the length of the ribbon of 11-AGNR30c to be synthesized) is controlled, for example, by the planar shape (its length) of the underlying substrate such as the Au (111) plane.

Following vacuum deposition to synthesize the polymer chain 20c as described above, the Au(111) surface is heated to 300° C.-350° C. at a heating rate of, for example, 1° C./min to 5° C./min. Holds from minutes to 1 hour. In the polymer chain 20b synthesized on the Au (111) surface at 300° C. to 350° C., the Cl atom is eliminated by breaking the C—Cl bond, while the F atom is eliminated by breaking the C—F bond. separation is suppressed. On the Au(111) surface at 300° C. to 350° C., deClification and C—C bond reactions are induced, and cyclization of the polymer chain 20c proceeds. As a result, 11-AGNR30c whose edges are terminated with F atoms, as shown in FIG. 9, is stably synthesized. On the Au (111) surface at 300 ° C. to 350 ° C., the elimination of F atoms is suppressed, and random bonding between polymer chains 20c, between polymer chains 20c and 11-AGNR30c, or between 11-AGNR30c. Bonding (bonding in the ribbon width direction Q) at points other than bonding points is suppressed.

11-AGNR30c synthesized using the precursor 10c, as described in the second embodiment (FIG. 4), is a ribbon corresponding to the length of the underlying substrate such as the Au (111) plane. synthesized in length.

Thus, in the synthesis of 11-AGNR30c using the precursor 10c, the desorption temperature difference of the Br, Cl, and F atoms bonded to the pentacene of the basic skeleton of the precursor 10c is utilized. That is, first, desorption of the Br atom, which has the lowest desorption temperature, and a C—C bond reaction are induced by heating at a predetermined temperature to synthesize the polymer chain 20c elongated in the length direction. Then, the elimination of the Cl atom with the intermediate elimination temperature and the C—C bond reaction are induced by heating at a higher temperature, the polymer chain 20c is cyclized, and 11-AGNR30c is synthesized. As a result, 11-AGNR30c having a long ribbon length and suppressed occurrence of defects is stably synthesized.

Following the heating for synthesizing 11-AGNR30c as described above, when the Au (111) plane is further heated at a high temperature, if the 11-AGNR30c group adjacent to the ribbon width direction Q exists on the Au (111) plane, they can be joined in the ribbon width direction Q.

FIG. 10 is an explanatory diagram of AGNR junction synthesis according to the fourth embodiment.
For example, following heating to synthesize 11-AGNR30c, the Au(111) surface is heated to 400° C. to 450° C. and held for 10 minutes to 1 hour. In 11-AGNR30c synthesized on the Au (111) surface at 400° C. to 450° C., the F atom is eliminated by breaking the C—F bond. On the Au (111) plane at 400 ° C. to 450 ° C., when the 11-AGNRs 30c extending parallel to the ribbon length direction P (11-AGNRs 31c and 32c in FIG. 10) are adjacent to each other in the ribbon width direction Q, , de-F and C—C bond reactions are induced. As a result, an AGNR (11-AGNR junction) 40c in which 11-AGNR 30c are six-membered ring-joined in the ribbon width direction Q is synthesized. Here, as an example, the plane L-shaped 11-AGNR junction 40c is illustrated.

As described in the second embodiment (FIGS. 5 and 6), the 11-AGNR junction 40c is synthesized with a planar shape corresponding to the planar shape of the underlying substrate such as the Au (111) plane. be.

Next, a fifth embodiment will be described.
An example in which AGNR synthesized using the above precursor is used in a semiconductor device will be described as a fifth embodiment. Here, as a semiconductor device, a field effect transistor (FET) in which a pair of electrodes serving as a source and a drain are connected by AGNR, that is, a field effect transistor (FET) using AGNR as a channel is taken as an example.

11 to 16 are explanatory diagrams of the method for manufacturing a semiconductor device according to the fifth embodiment. Hereinafter, description will be made in order with reference to FIGS. 11 to 16. FIG.
11A and 11B are diagrams showing an example of a metal layer forming process, in which (A) is a schematic plan view and (B) is a schematic cross-sectional view taken along line L11-L11 of (A).

First, as shown in FIGS. 11A and 11B, a metal layer 120 is formed on an insulating substrate 110 and patterned by electron beam lithography and dry etching.

Here, for the insulating substrate 110, for example, a mica substrate which is cleaved to expose a clean surface is used. The insulating substrate 110 is not particularly limited as long as it has insulating properties and a flat crystal surface. The insulating substrate 110 may be a mica substrate, a c-plane sapphire crystal substrate, a magnesium oxide (MgO) crystal substrate, or the like. Here, a case where a cleaved mica substrate is used as the insulating substrate 110 is taken as an example.

A metal layer 120 is formed on the insulating substrate 110 . The metal layer 120 is the underlying layer for synthesizing AGNR or AGNR junctions as described later. For example, Au is vapor-deposited and deposited as the metal layer 120 to a film thickness of 10 nm to 50 nm on the cleaved surface of the mica substrate, which is the insulating substrate 110 . When Au is deposited as the metal layer 120, the insulating substrate 110 is heated to 400° C. to 550° C. to improve the orientation of the Au (111) plane. In addition to Au, Cu, Ni, Rh, Pd, Ag, Ir, Pt, or the like may be used for the metal layer 120 . By appropriately selecting the type of the insulating substrate 110, an epitaxial crystal plane of the metal layer 120 using these metals can be obtained.

The metal layer 120 formed on the insulating substrate 110 is then patterned. The elimination of the X, Y and Z groups such as halogen atoms of the precursor as described above and the C—C bond reaction that occurs after the elimination are not effectively induced on the insulating substrate 110 . Therefore, the metal layer 120 is patterned, and the position and planar shape of the patterned metal layer 120 control the position and planar shape of the AGNR or AGNR junction synthesized thereon. AGNR changes in physical properties from semiconducting to metallic with increasing ribbon width. When AGNR is used in an FET, the connection region between the pair of electrodes, which are the source and the drain, is metallic, and the channel region between them is semiconducting. The position and planar shape of the metal layer 120 are designed so as to be synthesized. For example, as shown in FIG. 11(A), a pair of wide regions 121 having a width W1 and a narrow region 122 having a width W2 narrower than the width W1 are formed between the pair of wide regions 121. The position and planar shape of layer 120 are designed. For example, the width W1 is set to 50 nm or more, and the width W2 is set to 1 nm to 5 nm. The length L of narrow region 122 determines the length of the semiconducting region of the synthesized AGNR junction, ie, the channel length of the resulting FET. For example, the length L is set to 100 nm to 500 nm.

When patterning the metal layer 120 to a predetermined position and planar shape, first, a resist material such as an electron beam resist is formed by spin coating or the like, and a mask pattern for etching the metal layer 120 is formed. Using this as a mask, etching is performed by Ar ion milling or the like to form a metal layer 120 having a pattern as shown in FIG. 11(A).

FIG. 12 is a diagram showing an example of the AGNR junction synthesizing process, in which (A) is a schematic plan view and (B) is a schematic cross-sectional view taken along line L12-L12 of (A). Also, FIG. 13 is a diagram showing an example of the AGNR junction, and is an enlarged schematic diagram of the X portion of FIG.

After patterning the metal layer 120, an AGNR junction 130 is synthesized on the metal layer 120 as shown in FIGS. 12A and 12B.
When synthesizing the AGNR junction 130, for example, the surface of the metal layer 120 on the insulating substrate 110 is cleaned in the same manner as described in the second to fourth embodiments. This surface cleaning treatment removes resist residues (organic contaminants) adhering to the surface of the metal layer 120 and improves the flatness of the crystal plane of the metal layer 120 . The AGNR junction 130 is synthesized in-situ on the metal layer 120 in an ultra-high vacuum chamber without exposing the surface-cleaned metal layer 120 to the atmosphere.

Synthesis of the AGNR junction 130 uses a precursor having a structure like formula (2) as described in the first embodiment (and the second to fourth embodiments). When the precursor is deposited on the metal layer 120, the deposited film thickness is set to 1 ML to 1.5 ML so that the precursor has a two-dimensional close-packed structure on the metal layer 120. FIG. First, the precursor vapor-deposited on the metal layer 120 is heated at a temperature higher than the desorption temperature of the X group bonded to the C atom of the aromatic ring and lower than the desorption temperature of the Y group and the Z group. A precursor polymer, ie, a polymer chain, is synthesized by elimination of the X group and a CC bond reaction. Then, heating is performed at a condition equal to or higher than the elimination temperature of the Y group and lower than the elimination temperature of the Z group, and the elimination of the Y group and the CC bond reaction cause cyclization of the polymer chain, that is, AGNR. is synthesized. Next, heating is performed under conditions equal to or higher than the elimination temperature of the Z group, and the elimination of the Z group and the C—C bond reaction synthesize a six-membered ring conjugate between adjacent AGNRs, that is, the AGNR junction 130. .

In this way, a precursor having a structure as represented by formula (2) is used to synthesize polymer chains, AGNR, and AGNR junctions 130 on the metal layer 120 having a predetermined planar shape, thereby forming the metal layer 120. An AGNR junction 130 having a planar shape corresponding to the planar shape is synthesized. That is, a relatively wide AGNR junction portion 131 as shown in FIGS. 12 and 13 is synthesized on the wide region 121 of the metal layer 120, and a relatively wide AGNR junction portion 131 is synthesized on the narrow region 122 of the metal layer 120 in FIGS. A relatively narrow AGNR junction 132 as shown at 13 is synthesized. By forming the wide region 121 and the narrow region 122 of the metal layer 120 with predetermined widths W1 and W2 (<W1), respectively (FIG. 11), the AGNR junction portion 131 has a width that exhibits metallicity. , and is synthesized with a width such that the AGNR junction portion 132 exhibits semiconductor properties. Thereby, an AGNR junction 130 having a pair of metallic AGNR junction portions 131 and a semiconducting AGNR junction portion 132 therebetween is synthesized on the metal layer 120 .

14A and 14B are diagrams showing an example of the electrode forming process, in which (A) is a schematic plan view and (B) is a schematic cross-sectional view taken along line L14-L14 of (A).
After synthesizing the AGNR junction 130, as shown in FIGS. 14A and 14B, electrodes 140a and 140b used as a source and a drain are formed on the metallic AGNR junction portions 131 at both ends thereof. It is formed.

When forming the electrodes 140a and 140b, for example, electron beam lithography, vapor deposition of electrode materials, and lift-off are performed to form the electrodes 140a and 140b on the metallic AGNR junction portions 131 at both ends of the AGNR junction 130. An electrode 140b is formed. For the electrodes 140a and 140b, for example, electrodes with a two-layer structure (Cr/Ti) having a titanium (Ti) layer and a chromium (Cr) layer laminated thereon are used. By forming the electrodes 140a and 140b on the metallic AGNR junction portion 131, the contact resistance therebetween can be reduced.

In forming the Cr/Ti electrodes 140a and 140b, first, a resist pattern for electrode formation is formed with a two-layer resist or the like by electron beam lithography, and then Ti and Cr are sequentially deposited by vapor deposition. . For example, the film thickness of Ti is set to 0.5 nm to 1 nm, and the film thickness of Cr is set to 30 nm to 50 nm. After deposition of Ti and Cr, lift-off removes the resist pattern and the Ti and Cr deposited thereon. As a result, the electrodes 140 a and 140 b are formed on the metallic AGNR junction portions 131 at both ends of the AGNR junction 130 .

The metal layer 120 under the semiconducting AGNR junction portion 132 located in the middle portion of the AGNR junction 130 is removed by wet etching as described later. Therefore, it is desirable that the electrodes 140 a and 140 b formed here have a sufficient etching selectivity with respect to the metal layer 120 . When Au is used for the metal layer 120 and a potassium iodide (KI) aqueous solution as described later is used as an etchant for wet etching, Cr/Ti, which has sufficient etching resistance to the KI aqueous solution, is used for the electrode 140a and the electrode. It is suitable as a material for 140b.

15A and 15B are diagrams showing an example of a gate stack structure forming process, in which FIG. 15A is a schematic plan view, and FIG. 15B is a schematic cross-sectional view taken along line L15-L15 of FIG.
After forming the electrodes 140a and 140b, as shown in FIGS. 15A and 15B, a gate insulating layer 150 and a gate insulating layer 150 are formed on the semiconducting AGNR junction 132 located in the middle of the AGNR junction 130. As shown in FIGS. A gate stack structure, which is a stack of electrodes 160, is formed. For example, electron beam lithography, vapor deposition of insulating and electrode materials, and lift-off similar to the formation of electrodes 140a and 140b described above are performed to form a gate stack structure of gate insulating layer 150 and gate electrode 160. FIG.

In forming the gate stack structure, first, a resist pattern for forming the gate stack structure is formed using a two-layer resist or the like by electron beam lithography. For example, the gate length of the gate electrode 160 is designed to be 50 nm. Here, the metal layer 120 under the semiconducting AGNR junction portion 132 located in the middle portion of the AGNR junction 130 is removed by wet etching as described later. Therefore, a resist pattern for forming the gate stack structure is formed so that a gap 170 into which an etchant for wet etching can enter is formed between the gate stack structure to be formed and the electrodes 140a and 140b.

Next, an insulating material for the gate insulating layer 150 and an electrode material for the gate electrode 160 are sequentially deposited on the formed resist pattern by vapor deposition. For example, yttrium oxide (Y ₂ O ₃ ) with a thickness of 5 nm to 10 nm is deposited as the gate insulating layer 150 . Y ₂ O ₃ is formed by depositing yttrium (Y) metal in a vacuum chamber while introducing oxygen (O ₂ ) gas. Silicon oxide (SiO ₂ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ), lanthanum oxide (ZrO 2 ), and lanthanum oxide are deposited on the gate insulating layer 150 by a vapor deposition method that introduces Y ₂ O ₃ and similar O ₂ gas. (La ₂ O ₃ ), titanium oxide (TiO ₂ ), etc. may be used. Also, as the gate electrode 160, Cr/Ti is deposited with the same film thickness as the electrodes 140a and 140b.

The insulating material of the gate insulating layer 150 and the electrode material of the gate electrode 160 have sufficient etching resistance against an etchant when removing the metal layer 120 under the semiconducting AGNR junction portion 132 by wet etching as described later. It is desirable to have When Au is used for the metal layer 120 and a KI aqueous solution as described later is used as an etchant for wet etching, the insulating material and the electrode material have sufficient etching resistance to the KI aqueous solution, and the gate insulating layer 150 and as a material for the gate electrode 160 .

After depositing the insulating material of the gate insulating layer 150 and the electrode material of the gate electrode 160 on the resist pattern, the resist pattern and the insulating material and electrode material deposited thereon are removed by lift-off. As a result, the gate insulating layer 150 and the gate electrode 160 are formed on the semiconducting AGNR junction portion 132 located in the intermediate portion of the AGNR junction 130, spaced apart from the electrodes 140a and 140b.

16A and 16B are diagrams showing an example of the wet etching process, in which (A) is a schematic plan view and (B) is a schematic cross-sectional view taken along line L16-L16 of (A).
After forming the gate insulating layer 150 and the gate electrode 160, a portion of the metal layer 120 under the AGNR junction 130 is removed by wet etching, as shown in FIGS. 16A and 16B.

For example, as described above, when Au is used for the metal layer 120, a KI aqueous solution is used as an etchant for wet etching. A gap 170 is formed between the gate stack structure of the gate insulating layer 150 and the gate electrode 160 and the electrodes 140a and 140b. part of is removed. At that time, wet etching is performed so that at least the metal layer 120 below the semiconducting AGNR junction portion 132 of the metal layer 120 is removed. A cavity 180 is formed under the AGNR junction 130 by removing a portion of the metal layer 120 in this manner.

After removing the metal layer 120, for example, cleaning with pure water and rinsing with isopropyl alcohol are sequentially performed. After that, a supercritical drying process using carbon dioxide (CO ₂ ) gas is performed in order to prevent the AGNR junction 130 from being cut by the surface tension and capillary force of the solutions used in the cleaning and rinsing processes.

Through the steps described above, a semiconductor comprising an FET using an AGNR junction 130 suspended by a pair of electrodes 140a and 140b and a gate insulating layer 150 as shown in FIGS. A device 100 is obtained.

In this semiconductor device 100, a semiconducting AGNR junction portion 132 in the middle portion of the AGNR junction 130 is used as a channel, and electrodes 140a and 140b are connected to the metallic AGNR junction portions 131 at both ends, respectively. By controlling the potential of the gate electrode 160, the on/off of the semiconducting AGNR junction 132 connecting the electrodes 140a and 140b, that is, the channel is controlled. A high-speed, high-performance semiconductor device 100 that takes advantage of the high carrier mobility of AGNR is realized.

Next, a sixth embodiment will be described.
Here, another example in which AGNR synthesized using the above precursor is used for a semiconductor device will be described as a sixth embodiment.

FIG. 17 is a diagram showing a first example of a semiconductor device according to the sixth embodiment. FIG. 17 schematically shows a cross-sectional view of essential parts of a semiconductor device.
A semiconductor device 200 shown in FIG. 17 is an example of a top-gate FET, and includes a support substrate 210, an AGNR junction 220, electrodes 230a, 230b, a gate insulating layer 240, and a gate electrode 250. FIG.

As the support substrate 210, various insulating substrates such as sapphire, and various substrates provided with an inorganic or organic insulating material on at least the surface layer are used. An AGNR junction 220 is provided on such a support substrate 210 . The AGNR junction 220 is provided by transferring onto the support substrate 210 a material synthesized on a metal layer having a predetermined planar shape using a precursor having a structure as shown in formula (2).

In the semiconductor device 200, the AGNR junctions 220 have metallic AGNR junctions 221 with a predetermined width (not shown) at both ends, and narrower widths (not shown) at their intermediate portions. , having a semiconducting AGNR junction 222 is used. Electrodes 230a and 230b are connected to the metallic AGNR junctions 221 at both ends, respectively, and a gate electrode 250 is provided on the semiconducting AGNR junction 222 at the middle with a gate insulating layer 240 interposed therebetween. By controlling the potential of the gate electrode 250, the on/off of the semiconducting AGNR junction 222 connecting the electrodes 230a and 230b, that is, the channel is controlled. A high-speed, high-performance semiconductor device 200 that takes advantage of the high carrier mobility of AGNR is realized.

FIG. 18 is a diagram showing a second example of the semiconductor device according to the sixth embodiment. FIG. 18 schematically shows a cross-sectional view of essential parts of a semiconductor device.
A semiconductor device 300 shown in FIG. 18 is an example of a bottom-gate FET, and has a gate electrode 310, a gate insulating layer 320, an AGNR junction 330, electrodes 340a and 340b.

A conductive substrate is used for the gate electrode 310. For example, a semiconductor substrate such as a silicon (Si) substrate doped with an impurity element of a predetermined conductivity type is used. A gate insulating layer 320 is provided on such a gate electrode 310 , and an AGNR junction 330 is provided on the gate insulating layer 320 . The AGNR junction 330 is provided by transferring onto the gate insulating layer 320 a material synthesized on a metal layer having a predetermined planar shape using a precursor having a structure as shown in formula (2).

In the semiconductor device 300, the AGNR junctions 330 have metallic AGNR junctions 331 with a predetermined width (not shown) at both ends, and narrower widths (not shown) at their intermediate portions. , having a semiconducting AGNR junction portion 332 is used. Electrodes 340a and 340b are connected to the metallic AGNR junctions 331 at both ends, respectively. By controlling the potential of the gate electrode 310, the on/off of the semiconducting AGNR junction 332 connecting the electrodes 340a and 340b, that is, the channel is controlled. A high-speed, high-performance semiconductor device 300 that takes advantage of the high carrier mobility of AGNR is realized.

Moreover, the semiconductor device 300 as shown in FIG. 18 can also be used as an FET type gas sensor by utilizing the property of the AGNR junction 330 that the resistance changes upon molecular adsorption. In the semiconductor device 300 used as an FET-type gas sensor, changes in the relationship between the current flowing between the electrodes 340a and 340b and the voltage of the gate electrode 310 when gas is adsorbed on the AGNR junction 330 are measured. be. By using the AGNR junction 330, a highly sensitive FET-type gas sensor is realized.

FIG. 19 is a diagram showing a third example of the semiconductor device according to the sixth embodiment. FIG. 19 schematically shows a cross-sectional view of essential parts of a semiconductor device.
A semiconductor device 400 shown in FIG. 19 is an example of a Schottky barrier diode and has a supporting substrate 410, an AGNR junction 420, electrodes 430a and 430b.

As the support substrate 410, various insulating substrates such as sapphire, and various substrates provided with an inorganic or organic insulating material on at least the surface layer are used. An AGNR junction 420 is provided on such a support substrate 410 . The AGNR junction 420 is provided by transferring onto the support substrate 410 a material synthesized on a predetermined planar metal layer using a precursor having a structure as shown in formula (2).

Here, in semiconductor device 400 used as a Schottky barrier diode, the following is used as AGNR junction 420 . That is, it has a metallic AGNR junction portion 421 with a predetermined width (not shown) at both ends, and has a narrower width (not shown) at the intermediate portion of the bandgap or work function. An AGNR junction 420 is used having an AGNR junction portion 422a and an AGNR junction portion 422b of different semiconductivity.

For the semiconducting AGNR junction portion 422a and AGNR junction portion 422b, for example, those having different widths or different edge terminating groups are used.

When the widths are different from each other, a precursor such as formula (2) is applied on a metal layer having different widths for the portion where the AGNR junction portion 422a is synthesized and the portion where the AGNR junction portion 422b is synthesized. Synthesis is performed using

In addition, when the edge termination groups are different from each other, a part of the metal layer is selectively synthesized using a precursor having the first Z group, followed by another part of the metal layer. Optionally, the synthesis is performed using a precursor with a second Z group that is different from the first Z group. Alternatively, by synthesizing an AGNR junction, selectively introducing a first Z group on some edges of the synthesized AGNR junction, and selectively introducing a second group on other edges if necessary. . In this way, a structure is obtained in which the AGNR junction portion 422a and the AGNR junction portion 422b whose edges are terminated with different Z groups are connected.

The AGNR junction 420 is provided with such semiconductor AGNR junctions 422a and 422b as well as metallic AGNR junctions 421 at both ends. Electrodes 430a and 430b are connected to the metallic AGNR junctions 421 at both ends, respectively. One electrode 430a is made of a material (such as Cr) that makes a Schottky connection with the other AGNR junction portion 421, and the other electrode 430b is made of a material that makes an ohmic connection with the other AGNR junction portion 421 (such as Ti). ) is used.

According to the semiconductor device 400 having the above configuration, a Schottky barrier diode having excellent diode characteristics is realized.
The semiconducting AGNR junctions 222, 332, 422a, and 422b may be provided on a material having a doping function therefor, such as a so-called Self-Assembled Monolayer (SAM).

Next, a seventh embodiment will be described.
The semiconductor devices 100, 200, 300, 400, etc. described in the fifth and sixth embodiments can be mounted on various electronic devices (or electronic equipment). For example, it can be used in various electronic devices such as computers (personal computers, supercomputers, servers, etc.), smart phones, mobile phones, tablet terminals, sensors, cameras, audio equipment, measuring devices, inspection devices, and manufacturing devices.

FIG. 20 is a diagram illustrating an electronic device. FIG. 20 schematically shows an example of an electronic device.
As shown in FIG. 20, for example, the semiconductor device 100 as shown in FIG. As described above, the semiconductor device 100 includes high-speed, high-performance FETs that take advantage of the high carrier mobility of the AGNR junction 130 . A high-speed, high-performance electronic device 500 equipped with such a semiconductor device 100 is realized.

Here, the semiconductor device 100 as shown in FIG. 16 is used as an example, but other semiconductor devices 200, 300, 400, etc. can be similarly mounted on various electronic devices.

10a, 10b, 10c precursor 11, 12, 13 compound 20a, 20b, 20c polymer chain 30a, 30b, 31a, 31b, 32a, 32b 7-AGNR
30c, 31c, 32c 11-AGNR
40a, 40b 7-AGNR junction 40c 11-AGNR junction 100, 200, 300, 400 Semiconductor device 110 Insulating substrate 120 Metal layer 121 Wide region 122 Narrow region 130, 220, 330, 420 AGNR junction 131, 132, 221, 222 , 331, 332, 421, 422a, 422b AGNR junction part 140a, 140b, 230a, 230b, 340a, 340b, 430a, 430b electrode 150, 240, 320 gate insulating layer 160, 250, 310 gate electrode 170 gap 180 cavity 210, 410 support substrate 500 electronic device P ribbon length direction Q ribbon width direction W1, W2 width L length

Claims (5)

Synthesizing a second compound represented by the following general formula (2) by converting the amino group of a first compound having a Z group and an amino group represented by the following general formula (1) into a Y group process and
and converting the hydrogen atom bonded to the carbon atom of the aromatic ring of the second compound into an X group to synthesize a third compound represented by the following general formula (3). Production method.

[In the general formulas (1) to (3), s is an integer of 1 to 3, t is an integer of 0 to 4, and the X group, the Y group, and the Z group are the binding energy with the carbon atoms of the aromatic ring. is a group that increases in the order of C—X bond, CY bond, and C—Z bond. ] From the group of compounds represented by the following general formula (4), mutual elimination of X groups and bonding between carbon atoms of the aromatic rings from which the X groups are eliminated are represented by the following general formula (5) a step of synthesizing a first polymer that
a step of synthesizing a second polymer represented by the following general formula (6) by elimination of the Y group from the first polymer and bonding between carbon atoms of the aromatic ring from which the Y group has been eliminated; A method for producing graphene nanoribbons, comprising:

[In the general formulas (4) to (6), s is an integer of 1 to 3, t is an integer of 0 to 4, n is the degree of polymerization, and X, Y and Z are aromatic ring carbon atoms A group in which the bond energy with an atom increases in the order of C—X bond, CY bond, and C—Z bond. ] synthesizing the first polymer comprises heating the group of compounds at a first temperature;
3. The method of claim 2, wherein synthesizing the second polymer comprises heating the first polymer at a second temperature higher than the first temperature. . From the synthesized second polymer group, the second polymers are six-membered ring-bonded by mutual elimination of the Z groups and bonding between the carbon atoms of the aromatic rings from which the Z groups have been eliminated. 4. The method for producing graphene nanoribbons according to claim 2 or 3, further comprising synthesizing a third polymer. Claim citing Claim 3, characterized in that the step of synthesizing the third polymer comprises heating the group of the second polymers at a third temperature that is higher than the second temperature. 5. The method for producing graphene nanoribbons according to 4.

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