Crystalline carbon nanotube films

Abstract

To provide a crystalline film of carbon nanotubes, and a method and apparatus for manufacturing a crystalline film of carbon nanotubes.SOLUTION: A membrane is electrically charged to a polarity. A surface of carbon nanotubes (CNTs) in a solution is caused to acquire a charge of the polarity. The solution is filtered through the membrane. An electromagnetic repulsion between the membrane of the polarity and the CNTs of the polarity causes the CNTs to spontaneously align to form a crystalline structure.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates generally to manufactured arrangements of carbon nanotubes, and methods and apparatus for said manufacture. More particularly, the present invention relates to crystalline films of carbon nanotubes, and methods and apparatus for manufacturing crystalline films of carbon nanotubes. [Background technology]

[0002] Definitions within the scope of the exemplary embodiment are as follows:

[0003] (a) Carbon nanotube (CNT): A single-walled hollow open-ended cylindrical tube-like structure made essentially entirely of carbon atoms.

[0004] (b) Membrane: A sheet-like structure whose thickness is negligible compared to its surface area. For example, the thickness can be about 30 to 300 nanometers (nm) compared to a surface area of ​​1 square inch (6.45 square centimeters).

[0005] (c) Crystalline CNT (CCNT), crystalline structure of CNT: This refers to CNTs arranged so that the centers of individual CNTs form a periodic arrangement (lattice) in the cross section of the CNT film. For example, CNTs can be arranged in a hexagonal lattice, in which case the centers of any three nearest-neighbor CNTs form an equilateral triangle.

[0006] (d) Crystalline CNT film (CCF): A film formed from CNTs in which the CNTs are more crystalline than non-crystalline. A validation method-based definition of CCF is shown in Figure 4 herein and will be explained later.

[0007] Carbon nanotubes have several remarkable physical properties and have widespread applications in electronics, optics, and materials engineering. CNTs are among the highest conductors of electricity, with the highest amperage of any material. CNTs are also among the strongest materials, with a tensile strength approximately 100 times that of steel.

[0008] CNTs also have many applications in optics, especially when the energy of carbon nanotube excitons is in the infrared telecommunications range.CNTs also have many promising applications in energy science, including supercapacitors, photovoltaics, and batteries.

[0009] Some applications of carbon nanotubes rely on isolating them and incorporating them as individuals into electronic or optical devices. However, other applications involve large numbers of carbon nanotubes in thick or thin films. These films of nanotubes are typically disordered, meaning the CNTs are not arranged in any particular sequence. Previously, in addition to disordered films of carbon nanotubes, crystalline ropes of carbon nanotubes have also been produced. However, the rope sizes were small (<50 nm in diameter) and the arrangement of the ropes themselves was irregular.

[0010] Furthermore, structurally, ropes differ substantially from membranes: the surface area of ​​a membrane is similar to the cross-sectional area of ​​the rope, and the thickness of the membrane is similar to the length of the rope, so that, as in the case of membrane structures, the thickness of a rope structure is no longer negligible relative to the surface area.

[0011] The illustrative embodiments recognize that arranging carbon nanotubes into a monolithic crystal is desirable for many applications. CCFs are an example of a monolithic crystal of ordered CNTs contemplated herein. For example, for electronics, hexagonally ordered CCFs have the highest possible density of nanotubes and therefore the highest ampere capacity. As another example, for optical applications, this high density of nanotubes results in stronger optical activity. Stronger optical activity leads to brighter emission for applications relying on carbon nanotube luminescence and stronger nonlinearity for optical applications that rely on carbon nanotubes' strong chi-3 optical nonlinearity. For mechanical applications, nanotube crystalline films would be expected to be stronger than films of disordered nanotubes.

[0012] Exemplary embodiments describe structures of monolithic crystals of regularly aligned CNTs, such as the CCFs described herein, and methods for fabricating them. Exemplary embodiments provide methods for forming uniformly dense films of crystalline carbon nanotubes. CCFs fabricated by exemplary embodiments are readily scalable to wafer-sized films using the described processes. Such wafer-sized films are particularly useful in the fabrication of semiconducting and / or metallic films using wafers of appropriate substrate materials.

[0013] Furthermore, the method of the exemplary embodiment produces polycrystalline films, i.e., films containing multiple crystalline domains. Experiments have shown that this method can produce polycrystalline domains, each approximately 25 nm x 25 nm in size, with domains consisting of more than 100 CNTs observed. In other words, the lattice observed in the experiment was found to have a repeating triangular structure forming a hexagonal lattice, with a domain size of approximately 25 nm x 25 nm. The lattice constant was approximately 1.6 nm. The overall diameter of the experimentally fabricated CCF was 1 inch (2.54 cm), and the thickness was tunable from 30 nm up to 300 nm. It should be noted that within the contemplation of the exemplary embodiment, a domain is a collection of multiple crystalline structures in which two or more crystalline structures share one or more nanotubes. Summary of the Invention

[0014] Exemplary embodiments provide methods, apparatus, and articles of manufacture. One embodiment includes a method for charging a membrane to one polarity. This embodiment causes carbon nanotubes (CNTs) in a solution to acquire a charge of this polarity on their surfaces. This embodiment filters the solution through the membrane, and the electromagnetic repulsion between the membrane of this polarity and the CNTs of this polarity causes the CNTs to spontaneously align and form a crystalline structure. Thus, this embodiment produces a crystalline film of carbon nanotubes.

[0015] Another embodiment further includes, as part of the filtration, assisting the solution in filtering through the membrane, which assisting includes applying pressure to one side of the membrane. Thus, this embodiment provides an auxiliary method for fabricating a crystalline film of carbon nanotubes.

[0016] In another embodiment, the pressure is a negative pressure on the filtrate side of the membrane. Thus, this embodiment aids in the fabrication of crystalline films of carbon nanotubes using a specific type of pressure.

[0017] In another embodiment, the pressure is a positive pressure on the solution side of the membrane. Thus, this embodiment aids in the fabrication of crystalline films of carbon nanotubes using a specific type of pressure.

[0018] Another embodiment further exposes the membrane to a plasma, which imparts a negative charge to the membrane, and the CNTs in the solution are also negatively charged. Thus, this embodiment fabricates a crystalline film by aligning the nanotubes on the membrane.

[0019] In another embodiment, a powder containing CNTs is mixed with a liquid medium and a surfactant to form a solution, where the surfactant molecules have a charge of this polarity and the surfactant molecules attach to the CNTs, thereby imparting this charge polarity to the CNTs. This embodiment therefore fabricates a crystalline film by causing the nanotubes to acquire electrical properties that help align them on the membrane.

[0020] In another embodiment, the CNTs are single-walled carbon nanotubes. Thus, this embodiment produces a crystalline film of a particular type of carbon nanotube.

[0021] In another embodiment, the membrane is porous to the liquid medium of the solution but impermeable to the CNTs. Thus, this embodiment uses a particular type of membrane to fabricate the crystalline film.

[0022] In another embodiment, the crystalline structure is part of a polycrystalline structure of CNTs, and the polycrystalline structure of CNTs forms a crystalline carbon nanotube film (CCF). Thus, this embodiment fabricates a polycrystalline film of carbon nanotubes.

[0023] In another embodiment, the crystalline structure includes at least three CNTs arranged with their cylindrical axes in an equilateral triangle. Thus, this embodiment produces a polycrystalline film of carbon nanotubes, in which the nanotubes are organized in a specific crystalline structure.

[0024] One embodiment places a membrane containing a crystalline carbon nanotube film (CCF) on a transfer surface, with a separation medium interposed between the CCF and the transfer surface. This embodiment removes the separation medium. This embodiment removes the membrane. This embodiment anneals the CCF, which removes surfactant molecules from the CCF and bonds the CCF to the transfer surface. This embodiment thus prepares the CCF for use in the fabrication of semiconducting and / or metallic films.

[0025] Another embodiment further provides a denaturant to the CCF before annealing, which modifies the charge of the surfactant molecules in the CCF, thus purifying the CCF for use in manufacturing.

[0026] Another embodiment further heats the transfer surface containing the CCF to a temperature in a chamber as part of the anneal while maintaining a vacuum level in the chamber, thus bonding the CCF to a wafer for use in manufacturing.

[0027] Another embodiment further applies pressure to the membrane to evenly distribute the separation medium between the CCF and the displacement surface, thus providing a particular approach to bonding the CCF to a wafer for use in manufacturing.

[0028] Another embodiment further provides a desiccant, and the separation medium includes water, which removes the separation medium by drying the water. This embodiment uses the desiccant to dry the membrane. Thus, this embodiment prepares for removing the membrane.

[0029] Another embodiment further provides a solvent that dissolves the membrane as part of removing the membrane. Thus, this embodiment removes the membrane, leaving only the CCF for fabrication.

[0030] The novel features believed characteristic of the invention are set forth in the appended claims. However, the invention itself, as well as its preferred modes of use, further objects and advantages thereof, will best be understood by reading the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a block diagram of a simplified exemplary apparatus for producing a crystalline film of carbon nanotubes, according to an exemplary embodiment. [Figure 2] FIG. 1 is a block diagram of another simplified exemplary apparatus for producing a crystalline film of carbon nanotubes, according to an exemplary embodiment. [Figure 3] 1A-1C illustrate exemplary formations of a CCF according to an exemplary embodiment. [Figure 4] FIG. 1 illustrates a verification method for confirming the prevalence of crystalline structure in a given film, according to an example embodiment. [Figure 5] 1A-1C show microscopic images of cross sections of CCFs formed in accordance with exemplary embodiments. [Figure 6] FIG. 2 is a block diagram of one step of an exemplary process for transposing a CCF to a wafer according to an exemplary embodiment. [Figure 7] FIG. 10 is a block diagram of another step of an exemplary process for transposing a CCF to a wafer according to an exemplary embodiment. [Figure 8] FIG. 10 is a block diagram of another step of an exemplary process for transposing a CCF to a wafer according to an exemplary embodiment. [Figure 9] FIG. 10 is a block diagram of another step of an exemplary process for transposing a CCF to a wafer according to an exemplary embodiment. [Figure 10] 1 is a flow diagram of an exemplary process for manufacturing a CCF according to an exemplary embodiment. [Figure 11]1 is a flow diagram of an exemplary process for using CCF in the manufacture of semiconducting and / or metallic films according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0032] The exemplary embodiments used to describe the present invention generally address and solve the above-mentioned needs and other challenges related to the production of crystalline films of carbon nanotubes. The exemplary embodiments provide crystalline films of carbon nanotubes and methods and apparatus for producing crystalline films of carbon nanotubes.

[0033] One embodiment includes the CCF described herein. Another embodiment includes a method of manufacturing the CCF described herein. Another embodiment describes an apparatus for manufacturing the CCF described herein. Another embodiment describes a method of using the CCF in a process for manufacturing semiconducting and / or metallic films.

[0034] The method of an embodiment may be implemented as a software application configured to operate the CCF fabrication apparatus described herein. The software application implementing an embodiment may be configured as a modification to an existing wafer production system, as a separate application operating in conjunction with the existing wafer production system, as a stand-alone application, or some combination thereof.

[0035] For clarity of explanation, and without implying limitation, the exemplary embodiments are described using a simplified laboratory-sized apparatus. Armed with this disclosure, one skilled in the art will be able to scale the methods and apparatus described with respect to this laboratory-sized apparatus to commercial manufacturing capabilities without departing from the scope of the exemplary embodiments.

[0036] For clarity of explanation, and without implying limitation, the exemplary embodiments are described using simplified process steps suitable for a laboratory setting. Given this disclosure, one skilled in the art will be able to optimize, adjust, and adapt the described process steps for commercial manufacturing applications, and such adaptations are contemplated within the scope of the exemplary embodiments.

[0037] For clarity of explanation, and without implied limitation, exemplary embodiments are described using exemplary materials in various process steps. Given this disclosure, one skilled in the art will be able to modify the described materials or substitute functionally equivalent materials for purposes similar to those described in the process steps of an embodiment. Such substitutions are contemplated within the scope of the exemplary embodiments.

[0038] Additionally, the figures and exemplary embodiments use simplified illustrations of exemplary structures, elements, and devices. In the actual manufacture or use of the proposed CCF, there may be additional or different structures not shown or described herein without departing from the scope of the exemplary embodiments.

[0039] The differently shaded portions in the two-dimensional illustrations of the exemplary structures, layers, and formations are intended to represent different structures, layers, and formations in the exemplary fabrications described herein. Where applicable, the different structures, layers, and formations can be fabricated using suitable materials known to those skilled in the art to be in the same class as the materials described herein.

[0040] Specific shapes, locations, positions, or dimensions of shapes shown herein are not intended to limit the exemplary embodiments unless such characteristics are explicitly described as features of an embodiment. These shapes, locations, positions, dimensions, or certain combinations thereof have been selected solely for clarity of the drawings and description, and may be exaggerated, diminished, or otherwise modified from actual shapes, locations, positions, or dimensions that might be used in actual photolithography to achieve the objectives according to the exemplary embodiments.

[0041] When an embodiment is implemented in an application, a manufacturing process for a semiconducting film and / or a metallic film performs certain steps described herein. These steps of the manufacturing process are illustrated in some figures. Not all steps are required in a particular manufacturing process. Some manufacturing processes may perform these steps in a different order, combine certain steps, exclude or interchange certain steps, or perform some combination of these and other operations of steps without departing from the scope of the exemplary embodiments.

[0042] The CCFs of the embodiments described herein constitute a significant advance in materials science. Techniques for forming CCFs and making them readily usable in the wafer-based fabrication processes described herein do not currently exist. Therefore, a significant advance in materials science is achieved by forming a new material, i.e., a CCF. A significant advance in the fabrication of semiconducting and / or metallic films is achieved by the described process of transferring a CCF to a transfer surface, such as a wafer.

[0043] Exemplary embodiments are described with respect to, by way of example only, certain types of devices, timing, pressure values, speeds, dimensions, temperatures, angles, percentages, substances, structures, formations, layers, orientations, directions, steps, actions, planes, materials, numbers, systems, environments, components, and applications. Any particular manifestation of these and other similar artifacts is not intended to limit the invention. Any suitable manifestation of these and other similar artifacts may be selected within the scope of the exemplary embodiments.

[0044] The examples in this disclosure are used for clarity of explanation only and do not limit the exemplary embodiments. Additional structures, acts, actions, tasks, activities, and operations are conceivable from this disclosure and are contemplated within the scope of the exemplary embodiments.

[0045] The advantages listed herein are merely examples, and are not intended to limit the exemplary embodiments. Particular exemplary embodiments may realize additional or different advantages. Furthermore, particular exemplary embodiments may have some, all, or none of the advantages listed above.

[0046] 1, which shows a block diagram of a simplified exemplary apparatus for producing a crystalline film of carbon nanotubes according to an exemplary embodiment. The apparatus 100 includes a vessel 102 having a solution 104 of CNT powder and a suitable medium held therein.

[0047] It should be noted that solution 104 can be a colloidal solution that ultimately separates into a powder and a medium. In one embodiment, the CNT powder is a powder of primarily semiconductive single-walled nanotubes with an average diameter of approximately 1.41 nm. In one embodiment, the medium into which the powder is mixed to form solution 104 is a solution of water and a suitable surfactant, such as, but not limited to, sodium dodecylbenzene sulfonate. It is desirable to remove large nanotube bundles and amorphous carbon from solution 104. To achieve this removal, solution 104 can be centrifuged to separate these and other large / heavy particulate matter from solution 104.

[0048] Exemplary embodiments recognize that surfactants in the medium introduce electrically polar molecules, i.e., molecules that are electrically neutral overall but have a positive charge on one side and a negative charge on the other. The surfactant molecules bond to or otherwise associate with the CNTs in the powder. As a result, the surfaces of the CNTs become electrically charged. In the exemplary case where the surfactant is sodium dodecylbenzenesulfonate, negative charges associate with the surfaces of the CNTs in solution 104. In general, any component of solution 104 that can attach to and impart a charge to the CNTs can be adapted for use in solution 104.

[0049] The filter 106 is a membrane that is porous to the liquid of the solution 104 but not to the CNTs. In other words, the filter 106 is designed to block the passage of particles of a size comparable to that of the CNTs. In one non-limiting example, the filter 106 has a pore size of 0.05 micrometers (μm), such as a Whatman Nuclepore track-etched polycarbonate hydrophilic membrane with a pore size of 0.05 μm.

[0050] One embodiment imparts a charge to the membrane 106. In one non-limiting exemplary case, the membrane 106 is exposed to an air plasma, which imparts a negative charge to the membrane 106. It is important to note that the charge imparted to the membrane 106 should be of the same electrical polarity as the charge imparted to the CNTs by the surfactant. If the CNTs in the solution 104 are negatively charged, then the membrane 106 should also be negatively charged. If the CNTs in the solution 104 are positively charged, then the membrane 106 should also be positively charged.

[0051] The like polarity of the charges on the CNTs and membrane 106 creates an electromagnetic repulsion between the CNTs and membrane 106. This repulsion allows the CNTs to move relative to each other and relative to membrane 106 in such a way that, as solution 104 is filtered through membrane 106, the CNTs spontaneously align into the lattice and larger polycrystalline structures described above.

[0052] Membrane 106 can be held in place by any suitable mechanism, such as support 108. Support 108 or other suitable structure holds filter 106 in flow from the solution side to the filtrate side of device 100. Container 102 forms the solution side of device 100. A filtrate capture mechanism, such as a funnel-stopper assembly 110 coupled to container 112, forms the filtrate side of device 100.

[0053] Filtration of solution 104 through membrane 106 should be performed at a pace that allows the CNTs an opportunity to migrate and align as described herein. In one non-limiting case, the filtration rate is set so that the gravity-assisted filtration rate is a threshold filtration rate, and the desired filtration rate is slightly but not significantly greater than this threshold rate, for example, within a 10 percent tolerance band of the threshold rate. In one exemplary case, the filtration rate was set at 0.8 milliliters per hour.

[0054] In one embodiment, the desired filtration rate is achieved by applying negative pressure, i.e., a partial vacuum, to the container 112 on the filtrate side of the device 100. For example, a vacuum pump 114 can be coupled to the container 112 to draw the filtrate 116 through the membrane 106 at the desired rate.

[0055] The filtration rate is a factor of atmospheric pressure, density altitude, temperature of the solution 104, ambient temperature, and the negative or positive pressure applied. When negative pressure is applied as a filtrate-side vacuum, this vacuum can be adjusted to adjust the filtration rate, taking into account other variables that affect the filtration rate.

[0056] 2, which shows a block diagram of another simplified exemplary apparatus for producing crystalline films of carbon nanotubes, according to an exemplary embodiment. In apparatus 200, container 102, solution 104, membrane 106, support 108, and assembly 110 are all arranged and operate in the manner of apparatus 100 of FIG.

[0057] In one embodiment, the desired filtration rate is achieved by applying positive pressure to the solution side of the device 200. For example, the vessel 102 is pressurized with an amount of positive pressure calculated to force the solution 104 through the membrane 106 at the desired filtration rate. A pressure pump 214 can be coupled to the vessel 102 to apply the positive pressure.

[0058] The filtration rate is a factor of atmospheric pressure, density altitude, temperature of the solution 104, ambient temperature, and the applied negative or positive pressure. When applying positive pressure as a solution side vacuum, this pressure can be adjusted to adjust the filtration rate, taking into account other variables that affect the filtration rate.

[0059] Solely for clarity of explanation, and without implied limitation, the subsequent description and figures will assume negatively charged CNTs, a negatively charged membrane, and the vacuum filtration process of FIG.

[0060] In one embodiment, the vacuum pressure is varied during filtration. For example, in a first stage, the vacuum pressure can be set below a low threshold, e.g., 2-3 Torr, for a first period, e.g., 5-6 hours. This low vacuum allows for slow filtration, e.g., at a rate of one drop per 200 seconds. This slow filtration over this period results in a thin crystalline film of CNTs. After this first stage, the membrane appears dark due to the thin crystalline film formed initially. Then, in a second stage, the vacuum pressure is increased to a second threshold, e.g., 8 Torr, for a second period. During this second period, the solution passes through the membrane at a rate of one drop per 90 seconds. To prevent prolonged surface tension from destroying the membrane as the final amount of solution passes through the membrane, the vacuum pressure is increased to a high threshold, e.g., approximately 1000 Torr, for a third period just before the solution runs out. Finally, the membrane is left to dry under the high threshold pressure.

[0061] The vacuum is assumed constant solely for clarity of explanation and to avoid distracting attention from other features being described without implying any limitations to the exemplary embodiments. From this disclosure, one skilled in the art can adjust the positive or negative pressure in combination with the other steps described, and such combinations are intended to fall within the scope of the exemplary embodiments.

[0062] Referring to Figure 3, this figure shows an exemplary formation of a CCF according to an exemplary embodiment. Figure 300 is a top view of a membrane 302 and a polycrystalline film of CNTs 304 formed thereon. Figure 301 is a cross-sectional view of membrane 302 and film 304.

[0063] Membrane 302 is an example of membrane 106 from Figure 1. Membrane 302 is charged with the same polarity as that associated with the CNTs in solution. Film 304 is deposited on the solution side of membrane 302 by a filtration process. As shown in simplified representative diagram 300, the CNTs in membrane 304 are generally aligned in direction 306 (represented by the parallel lines in membrane 304).

[0064] Diagram 301 shows that the CNTs are arranged into one or more domains 308, each domain 308 containing multiple CNTs. Furthermore, the CNTs within a domain 308 are organized into a triangular lattice 310 as described herein. A domain 308 may or may not be connected to another domain 308; i.e., two domains may or may not share a common CNT. Different domains 308 may contain different numbers of CNTs in the formation of a lattice 310. Although the CNTs within a domain are regularly arranged, i.e., arranged according to a lattice 310, the CNTs in one domain 308 need not be regularly arranged relative to the CNTs in another domain 308, i.e., they need not be organized as a lattice 310 relative to each other.

[0065] Referring to Figure 4, this figure illustrates a verification method for confirming the prevalence of crystalline structure in a given film according to an exemplary embodiment. A film of CNTs may have CNTs organized as a crystalline structure or lattice as described herein, or may have CNTs randomly positioned relative to one another. The film may contain more crystalline domains than randomly oriented CNTs, or may contain more randomly oriented CNTs than crystalline domains. A film with more crystalline domains than randomly oriented CNTs is considered a CCF, and the verification process described with respect to this figure determines whether the film is a CCF.

[0066] In this experiment, a given film is prepared for X-ray diffraction imaging. In this experiment, grazing incidence X-ray diffraction (XRD) is used to characterize the crystallinity of the aligned CNT arrays. The grazing incidence mode is particularly useful for measuring thin films. In this experiment, we observe low-angle diffraction from the CNT lattice, related to the lattice constant of >1 nm (as opposed to the much higher-angle diffraction from the carbon lattice of the constituent CNTs).

[0067] A film is assumed to be a CCF if the crystalline structures are unidirectionally aligned, as expected for crystalline carbon nanotubes. In this experiment, an X-ray beam is incident on the film at an angle θ from the normal to the plane of the film. If a given film is a CCF, a strong peak at approximately 2θ = 5.8° will be observed in the reflected X-ray signal for at least one orientation of the film relative to the X-ray beam, as shown in graph 402.

[0068] If a given film is not a CCF, due to the randomly oriented CNTs, the reflectance graph will not show a significant peak, as in graph 404. Furthermore, the lack of a significant peak in graph 404 remains substantially constant for any orientation of the film relative to the x-ray beam.

[0069] The 2θ value corresponds to the lattice spacing of the aligned nanotube array. When the film is CCF, a strong peak signal is observed across substantially the entire sample area of ​​the film, suggesting crystalline alignment of the nanotubes and uniform crystallinity across a significant portion of the film area.

[0070] A peak in a graph is a change in the slope of the graph from negative to positive to negative again within a region of the graph. The more abrupt the change or changes in slope, the more pronounced or strong the peak, and vice versa.

[0071] Graph 404 can be considered a baseline graph for measuring peaks in other graphs to detect the presence of crystalline alignment of nanotubes within a given film. A film is considered a CCF if there is a peak at only a single 2θ value in graph 402 for substantially all regions of the film. In contrast, when a film is not a CCF, smaller peaks may appear at multiple 2θ values, and these peaks are less pronounced compared to the peaks in graph 402. When a film contains exclusively or predominantly amorphous carbon nanotube structures, the film is not a CCF.

[0072] Referring to Figure 5, this figure shows a microscope image of a cross section of a CCF formed in accordance with an exemplary embodiment. Image 502 is a transmission electron microscope (TEM) image of the CCF. Image 502 shows a round cross section and a single domain of nanotubes arranged in a hexagonal crystalline structure. The hexagonal spacing between adjacent nanotubes in the crystalline structure of image 502 is on the order of 1.61 ± 0.04 nm.

[0073] Image 504 is a TEM diffractogram of an area of ​​the CCF. The periodic hexagonal arrangement of diffraction peaks in image 504 is characteristic of electrons diffracted from the object's hexagonal lattice. The spacing of the diffraction peaks is consistent with the lattice constant of 1.61 nm measured directly in image 502.

[0074] 6, which shows a block diagram of one step of an exemplary process for transferring a CCF to a wafer according to an exemplary embodiment. CCF 602 is an example of CCF 304 of FIG. 3, with the CNTs still attached to the charged surfactant molecules.

[0075] The transfer surface 604 is the surface of a suitable wafer substrate material. For example, but not limited to, the substrate 604 can be silicon and sapphire, both of which are commonly available in wafer form for manufacturing. Depending on the substrate material, some pre-treatment of the wafer may be useful. For example, an electrode pattern can be formed, or native oxide can be removed with buffered hydrofluoric acid.

[0076] The transfer surface 604 is the surface onto which the CCF 304 is to be laminated, deposited, or transferred from a membrane, such as membrane 302 of FIG. 3. To transfer the membrane 602, a liquid medium 606, such as water, is placed on the transfer surface 604. Note that as little as one drop of water may be sufficient to form a thin film of water on the wafer. A membrane 608, an example of membrane 302 of FIG. 3, is then placed on the liquid-covered transfer surface such that the CCF 602 is in contact with the liquid 606.

[0077] Although not shown in configuration 600, a suitable mechanism may apply pressure to membrane 608 to expel or evenly distribute liquid 606 beneath CCF 602. For example, a glass slide or sheet may be placed on top of membrane 608 and pressed to cause this distribution or expulsion.

[0078] 7, which shows a block diagram of another step of an exemplary process for transferring a CCF to a wafer, according to an exemplary embodiment. A desiccant 702 is applied to the structure 600. The desiccant 702 can be heat or some other suitable desiccant. For example, in one experiment, nitrogen gas was used as the desiccant 702 to dry the structure 600.

[0079] This drying step removes liquid 606 from composition 600 and also dries membrane 608. The result of this drying step is composition 700.

[0080] 8, a block diagram of another step of an exemplary process for transferring a CCF to a wafer is shown, according to an exemplary embodiment. A solvent 802 is applied to the configuration 700. The solvent 802 may be any suitable material capable of dissolving the membrane 608 without adversely affecting the CCF 602. For example, in one experiment, chloroform was used as the solvent 802 to dissolve the membrane 608.

[0081] This dissolution step removes membrane 608 from configuration 700. The result of this dissolution step is configuration 800.

[0082] 9, which shows a block diagram of another step of an exemplary process for transferring CCF to a wafer, according to an exemplary embodiment. Remove surfactant from CCF 602 layer. Optionally, provide a suitable denaturing agent 902 to the configuration 800 to denature the surfactant and / or remove polymer residues from previous steps. Nitric acid is one non-limiting example of the denaturing agent 902.

[0083] The surfactant is then removed from the CCF 602 by subjecting the configuration 800 to an annealing operation 904. One non-limiting way to perform the annealing 904 is to -7 The structure 800 (after optional modification) is heated to 500° C. for a period of time, e.g., 2 hours, in a vacuum furnace at 1000 Torr. The resulting CCF 906 is substantially free of surfactant molecules and is bonded to the transfer surface 604 of the wafer. The resulting wafer with the CCF layer of structure 900 is then ready for further device specific fabrication.

[0084] 10, which shows a flow diagram of an exemplary process for manufacturing a CCF according to an exemplary embodiment. Process 1000 can be implemented using apparatus 100 of FIG. 1 or apparatus 200 of FIG. 2.

[0085] A solution is formed using powdered CNTs in a suitable liquid and surfactant (Block 1002). A membrane of appropriate size is charged with a charge of the same polarity as that of the CNT-surfactant combination in the solution (Block 1004). An apparatus is configured to filter the solution using the charged membrane and pressure (Block 1006). The solution is assisted through the charged membrane at an appropriate filtration rate (Block 1008). Optionally, this pressure assistance can be adjusted in one or more steps during the filtration period as described herein (Block 1010). Process 1000 ends after depositing a film of CNTs and surfactant molecules on the membrane.

[0086] 11, which illustrates a flow diagram of an exemplary process for using CCF in the fabrication of semiconductive and / or metallic films according to an exemplary embodiment. Process 1100 can be performed using the wafers described with respect to FIGS. 6-9.

[0087] The surface of the wafer is prepared as a transfer surface to receive the CCF (block 1102). A liquid, such as water, is added to form an intermediate film between the CCF and the transfer surface (block 1104). The membrane assembly shown in Figure 3 is placed on the transfer surface so that the CCF contacts the liquid film (block 1106).

[0088] Optionally, pressure is applied to the membrane to expel or evenly distribute the liquid film beneath the CCF (block 1108). A suitable desiccant is used to dry the membrane and further dry out any residual liquid between the CCF and the displacement surface (block 1110). A suitable solvent is used to dissolve the membrane (block 1112). The surfactant in the CCF is denatured (block 1114). The remaining CCF contains substantially only crystalline carbon nanotubes.

[0089] The remaining CCF is annealed and remains in the displaced plane (block 1116), after which the process ends.

[0090] While certain steps and processes are described using certain structures, it is understood that, within the scope of the exemplary embodiments, the steps and / or processes can be adapted to achieve the results described herein. While certain materials are used in numerous layers or structures, it is understood that, within the scope of the exemplary embodiments, alternative materials or different but functionally equivalent materials can be used in place of the described materials in any layer described herein. Although certain methods are used in certain steps, it is understood that, within the scope of the exemplary embodiments, steps can be omitted, added, or modified in the described methods to achieve functionally equivalent results. Although certain operations are described as "steps," several operations can be combined to form a single step of the processes described herein. While certain orientations are referred to as "top" and "bottom" relative to the exemplary vertical orientation of the proposed device, it is understood that the device can be oriented laterally such that the top and bottom become left / right or right / left, or bottom and top, or front / back or back / front, depending on the orientation.

[0091] Thus, exemplary embodiments provide CCFs, methods of manufacturing CCFs, and methods of using CCFs in manufacturing semiconducting and / or metallic films. Where an embodiment, or portions thereof, is described with respect to one type of material, the manufacturing method, system or apparatus, software implementation, or portions thereof, may be adapted or configured for use with different manifestations of that material.

[0092] The present invention can be a material, apparatus, method, or computer program product, or combinations thereof, at any level of technical detail that allows integration. A computer program product can include a computer-readable storage medium having computer-readable program instructions thereon for causing a processor to carry out aspects of the present invention. As used herein, computer-readable storage medium, including but not limited to computer-readable storage devices, is not itself to be understood as a transitory signal, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating in a waveguide or other transmission medium (e.g., a light pulse traveling in a fiber optic cable), or an electrical signal transmitted by an electrical wire.

[0093] The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a corresponding respective computing / processing device, or may be downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, or a wireless network, or a combination thereof.

[0094] One embodiment of the present invention is as follows. Term [A1] charging the membrane to one polarity; Acquiring a charge of said polarity on the surface of carbon nanotubes (CNTs) in solution; filtering the solution through the membrane; The CNTs spontaneously align to form a crystalline structure due to the electromagnetic repulsion between the polar membrane and the polar CNTs. method. Term [A2] As part of said filtering, assisting said solution in filtering through said membrane. wherein said assisting comprises applying pressure to one side of said membrane. The method described in item [A1]. Term [A3] The method according to item [A2], wherein the pressure is a negative pressure on the filtrate side of the membrane. Term [A4] The method according to item [A2], wherein the pressure is a positive pressure on the solution side of the membrane. Section [A5] exposing the membrane to a plasma; wherein the plasma imparts a negative charge to the membrane, and the CNTs in the solution are also negatively charged; The method described in item [A1]. Item [A6] The method described in paragraph [A1], wherein the powder containing the CNTs is mixed with a liquid medium and a surfactant to form the solution, and the surfactant molecules have the polar charge, and the surfactant molecules attach to the CNTs, thereby imparting the polarity of charge to the CNTs. Item [A7] The method according to item [A1], wherein the CNT is a single-walled carbon nanotube. Item [A8] The method according to item [A1], wherein the membrane is porous to the liquid medium of the solution but impermeable to the CNTs. Item [A9] The method according to item [A1], wherein the crystalline structure is part of a polycrystalline structure of CNTs, and the polycrystalline structure of CNTs forms a crystalline carbon nanotube film (CCF). Term [A10] The method according to item [A1], wherein the crystalline structure comprises at least three CNTs whose cylindrical axes are arranged in an equilateral triangle. Section [A11] disposing a membrane including a crystalline carbon nanotube film (CCF) on the inversion surface, with a separation medium interposed between the CCF and the inversion surface; removing the separation medium; removing the membrane; annealing the CCF, wherein the annealing removes surfactant molecules from the CCF and bonds the CCF to the displacement surface. A method comprising: Item [A12] providing a denaturant to the CCF prior to the annealing; wherein the denaturing agent changes the charge of the surfactant molecules in the CCF. The method described in item [A11]. Section [A13] heating the transfer surface including the CCF to a temperature in a chamber as part of the annealing while maintaining a vacuum level in the chamber. The method according to paragraph [A11], further comprising: Section [A14] applying pressure to the membrane to evenly distribute the separation medium between the CCF and the displacement surface; The method according to paragraph [A11], further comprising: Section [A15] providing a desiccant, the separation medium comprises water, and the desiccant removes the separation medium by drying the water; drying the membrane using the desiccant; The method according to paragraph [A11], further comprising: Section [A16] Applying a solvent wherein the solvent dissolves the membrane as part of removing the membrane. The method described in item [A11]. Section [A17] An apparatus for producing crystalline carbon nanotube films (CCFs), comprising: a membrane having a charge of one polarity; a solution containing carbon nanotubes (CNTs), wherein the CNTs in the solution have acquired the polar charge; a filtration mechanism for filtering the solution through the membrane; Equipped with The CNTs spontaneously align into a crystalline structure due to the electromagnetic repulsion between the polar membrane and the polar CNTs. Device. Section [A18] an assisting mechanism that assists in filtering the solution through the membrane; wherein the assist mechanism applies pressure to one side of the membrane. The device according to item [A17]. Section [A19] The device described in paragraph [A18], wherein the assist mechanism applies negative pressure to the filtrate side of the membrane. Item [A20] The device described in item [A18], wherein the assist mechanism applies positive pressure to the solution side of the membrane. Section [A21] oxygen plasma The oxygen plasma imparts a negative charge to the membrane, and the CNTs in the solution are also negatively charged by a surfactant. The device according to item [A17]. Item [A22] An alignment component that aligns a membrane containing crystalline carbon nanotube film (CCF) on the dislocation surface. a separation medium is interposed between the CCF and the displacement surface; and a first remover applicator for removing the separation medium; a second remover applicator for removing the membrane; a chamber for annealing the CCF; wherein the annealing removes surfactant molecules from the CCF and bonds the CCF to the displacement surface. Device. Item [A23] Modifier Applicator wherein the denaturing agent changes the charge of the surfactant molecules in the CCF. The device according to item [A22]. Item [A24] A product, Carbon nanotube (CNT) membrane the CNTs are arranged in a crystalline structure within the film, the crystalline structure comprising at least three CNTs with their cylindrical axes arranged in an equilateral triangle, the crystalline structure being part of a domain, a plurality of domains forming a polycrystalline structure of CNTs, the polycrystalline structure of CNTs forming a crystalline carbon nanotube film (CCF). product. Item [A25] Substrate material wafer and the CCF is bonded to the transfer surface of the wafer. The product described in paragraph [A24].

[0095] Another embodiment of the present invention is as follows. Term [B1] charging the membrane to one polarity; Acquiring a charge of said polarity on the surface of carbon nanotubes (CNTs) in solution; filtering the solution through the membrane; Including, the filtering step further comprises assisting the solution in filtering through the membrane; said assisting comprising applying pressure to one side of said membrane; The method comprises the steps of: forming a crystalline structure by spontaneously aligning the CNTs due to an electromagnetic repulsive force between the polar membrane and the polar CNTs; applying pressure to the solution as a first step, setting a vacuum pressure at a first threshold for a first period of time; then, in a second stage, increasing the vacuum pressure to a second threshold value greater than the first value for a second period of time; and Then, in a third step, the method includes increasing the vacuum pressure to a third threshold value greater than the second value for a third period of time. Term [B2] The method according to item [B1], wherein the first threshold is a pressure lower than 2 to 3 Torr. Term [B3] The method of paragraph [B1], wherein the first threshold causes the filtration to occur at a rate of 1 drop per 200 seconds, and the second threshold causes the solution to pass through the membrane at a rate of 1 drop per 90 seconds during the second period. Term [B4] The method according to item [B1], wherein the pressure is a negative pressure on the filtrate side of the membrane. Term [B5] The method according to item [B1], wherein the pressure is a positive pressure on the solution side of the membrane. Term [B6] further comprising exposing the membrane to a plasma; The plasma imparts a negative charge to the membrane, and the CNTs in the solution are also negatively charged. The method described in item [B1]. Term [B7] The method according to item [B1], wherein the powder containing the CNTs is mixed with a liquid medium and a surfactant to form the solution, and the surfactant molecules have the polar charge, and the surfactant molecules attach to the CNTs, thereby imparting the polarity of charge to the CNTs. Term [B8] The method according to item [B1], wherein the CNT is a single-walled carbon nanotube. Term [B9] The method according to item [B1], wherein the membrane is porous to the liquid medium of the solution but impermeable to the CNTs. Term [B10] The method according to item [B1], wherein the crystalline structure is part of a polycrystalline structure of CNTs, and the polycrystalline structure of CNTs forms a crystalline carbon nanotube film (CCF). Item [B11] The method according to item [B1], wherein the crystalline structure comprises at least three CNTs whose cylindrical axes are arranged in an equilateral triangle. Item [B12] An apparatus for producing crystalline carbon nanotube films (CCFs), comprising: a membrane having a charge of one polarity; a container for containing a solution containing carbon nanotubes (CNTs) that have acquired the polar charge; a filtration mechanism for filtering the solution through the membrane; Equipped with the CNTs spontaneously align into a crystalline structure due to electromagnetic repulsion between the polar membrane and the polar CNTs; The filter further includes an assist mechanism for assisting the filtering of the solution through the membrane, the assist mechanism applying pressure to one side of the membrane. In the device, applying pressure to the solution as a first step, setting a vacuum pressure at a low threshold for a first period of time; then, in a second stage, increasing the vacuum pressure to a second threshold value greater than the first value for a second period of time; and Then, in a third stage, the apparatus includes increasing the vacuum pressure to a high threshold value greater than the second value for a third period of time. Item [B13] The apparatus according to item [B12], wherein the first threshold is a pressure lower than 2 to 3 Torr. Item [B14] The device described in paragraph [B12], wherein the first threshold causes the filtration to occur at a rate of 1 drop per 200 seconds, and the second threshold causes the solution to pass through the membrane at a rate of 1 drop per 90 seconds during the second period. Item [B15] The device described in paragraph [B12], wherein the assist mechanism applies negative pressure to the filtrate side of the membrane. Item [B16] The device according to item [B12], wherein the assist mechanism applies positive pressure to the solution side of the membrane. Item [B17] further comprising a plasma generator for generating oxygen plasma; The oxygen plasma gives the membrane a negative charge, and the CNTs in the solution are also negatively charged by the surfactant. The device according to item [B12]. Item [B18] A structure comprising a film of carbon nanotubes (CNTs), the CNTs are arranged in a crystalline structure within the film, the crystalline structure comprising at least three CNTs with their cylindrical axes arranged in an equilateral triangle, the crystalline structure being part of a domain, a plurality of domains forming a polycrystalline structure of CNTs, and the polycrystalline structure of CNTs forming a crystalline carbon nanotube film (CCF); structure.

Claims

1. charging the membrane to one polarity; allowing carbon nanotubes (CNTs) in solution to acquire charges of said polarity on their surfaces; filtering the solution through the membrane; Including, the filtering step further comprises assisting the solution in filtering through the membrane; said assisting comprising applying pressure to one side of said membrane; The method comprises the steps of: forming a crystalline structure by spontaneously aligning the CNTs due to an electromagnetic repulsive force between the polar membrane and the polar CNTs; applying the pressure a first step of setting a vacuum pressure at a first threshold for a first period of time, the first threshold being a pressure below 3 Torr; then, in a second stage, increasing the vacuum pressure to a second threshold value greater than the first threshold value for a second period of time; and and then, in a third step, increasing the vacuum pressure to a third threshold value greater than the second threshold value for a third period of time. The method comprising:

2. 2. The method of claim 1, wherein the third period begins just before the solution is depleted so as to prevent prolonged surface tension from disrupting the membrane as the remaining solution passes through the membrane.

3. The method of claim 1 , further comprising drying the membrane at the third threshold after the third period of time has elapsed.

4. The method of claim 1 , wherein the pressure is a negative pressure on the filtrate side of the membrane.

5. The method of claim 1 , wherein the pressure is a positive pressure on the solution side of the membrane.

6. further comprising exposing the membrane to a plasma; The plasma imparts a negative charge to the membrane, and the CNTs in the solution are also negatively charged. The method of claim 1.

7. 2. The method of claim 1, wherein to form the solution, a powder including the CNTs is mixed with a liquid medium and a surfactant, the surfactant molecules having the polar charge, and the surfactant molecules attach to the CNTs, thereby imparting the polarity of charge to the CNTs.

8. The method of claim 1 , wherein the CNTs are single-walled carbon nanotubes.

9. The method of claim 1 , wherein the membrane is porous to the liquid medium of the solution but impermeable to the CNTs.

10. The method of claim 1 , wherein the crystalline structure is part of a polycrystalline structure of CNTs, and the polycrystalline structure of CNTs forms a crystalline carbon nanotube film (CCF).

11. The method of claim 1 , wherein the crystalline structure comprises at least three CNTs arranged with their cylindrical axes in an equilateral triangle.

12. An apparatus for producing crystalline carbon nanotube films (CCFs), comprising: a membrane having a charge of one polarity; a container for containing a solution containing carbon nanotubes (CNTs) that have acquired the polar charge; a filtration mechanism for filtering the solution through the membrane; Equipped with the CNTs spontaneously align into a crystalline structure due to electromagnetic repulsion between the polar membrane and the polar CNTs; The filter further includes an assist mechanism for assisting the filtering of the solution through the membrane, the assist mechanism applying pressure to one side of the membrane. In the device, applying the pressure a first step of setting a vacuum pressure to a low threshold for a first period of time, the first threshold being a pressure below 3 Torr; then, in a second stage, increasing the vacuum pressure to a second threshold value greater than the first threshold value for a second period of time; and Then, in a third stage, increasing the vacuum pressure to a high threshold value greater than the second threshold value for a third period of time. The device comprising:

13. 13. The device of claim 12, wherein the third period begins just before the solution is depleted so as to prevent prolonged surface tension from disrupting the membrane as the remaining volume of solution passes through the membrane.

14. 13. The apparatus of claim 12, wherein after the third period of time, the membrane is dried at a third threshold.

15. The device of claim 12 , wherein the assist mechanism applies negative pressure to the filtrate side of the membrane.

16. The device of claim 12 , wherein the assist mechanism applies positive pressure to the solution side of the membrane.

17. further comprising a plasma generator for generating oxygen plasma; The oxygen plasma imparts a negative charge to the membrane, and the CNTs in the solution are also negatively charged by the surfactant.

13. The apparatus of claim 12.

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