RU2488188C2 - Method and device for application of nano-pattern on large area - Google Patents

Abstract

FIELD: nanotechnology.

SUBSTANCE: technique of application of nano-pattern uses the near-field photolithography, which provides a substrate with a layer sensitive to radiation, a rotatable mask having a nano-pattern on the outer surface, contact of the said nano-pattern with the said layer sensitive to radiation, the distribution of radiation through the said nano-pattern while rotating the said mask on the said layer sensitive to radiation, thereby an image is created having a size of the element in the range of less than 1 micron to about 1 nm in the said layer sensitive to radiation, and the said nano-pattern is able to be conformal nano-pattern which is consistent with the said layer sensitive to radiation on the surface of the said substrate.

EFFECT: creation of nano-patterns on substrates of a large area.

30 cl, 8 dwg

Description

Technical field

Embodiments of the invention relate to methods for applying a nanoparticle that can be used to pattern large substrates or substrates, for example, films that can be sold in rolls. Other embodiments of the invention relate to a device that can be used to template substrates and which can be used to implement embodiments of the method, including those described.

State of the art

This section describes the premises underlying the disclosed embodiments of the present invention. Applicants do not claim, either directly or indirectly, that the technical background discussed in this section formally constitutes the state of the art.

Nanostructuring is necessary for many existing applications and industries, as well as developing new technologies. Efficiency gains can be achieved for current applications in areas such as solar cells and LEDs, as well as, for example, but not limited to, next-generation storage devices.

Nanostructured substrates can be fabricated using techniques such as direct electron beam exposure, far-UV lithography, nanospheric lithography, nano-imprint lithography, near-field phase-shift lithography, and plasmon lithography.

Nanoimprint lithography (NIL) creates patterns by mechanical deformation of the imprint resist and subsequent processing. An imprint resist is usually a monomeric or polymeric compound that cures under the influence of heat or UV light during imprinting. There are several varieties of NIL. However, the two processes look the most important. These are thermoplastic nanoimprint lithography (TNIL) and nanoimprint lithography with stepwise shift and UV exposure (SFIL).

TNIL is the earliest and most advanced nanoimprint lithography. In the standard TNIL process, a thin layer of imprint resist (thermoplastic polymer) is applied to the sample substrate by centrifugation. Then a mold having predetermined topological patterns in contact with the sample is pressed against the sample under a predetermined pressure. When the thermoplastic polymer is heated above the glass transition temperature, the mold on the mold is pressed into the molten thermoplastic polymer film. After cooling the sample with an indented mold, the mold is separated from the sample, and the imprint resist remains on the surface of the sample substrate. The pattern does not pass through the imprint resist; on the surface of the sample substrate there is a residual thickness of the unchanged thermoplastic polymer film. The process of transferring a pattern, for example, reactive ion etching, can be used to transfer the pattern in a resist to the underlying substrate. Changing the residual thickness of the unaltered thermoplastic polymer film presents a problem with respect to uniformity and optimization of the etching process used to transfer the pattern to the substrate.

In the SFIL process, a UV curable liquid resist is applied to a sample substrate, and the mold is made of a transparent substrate, for example fused silica (silica glass). After the mold and the substrate of the sample are pressed together, the resist is cured using UV light and becomes solid. After separating the mold from the cured resist material, a pattern similar to that used in TNIL can be used to transfer the pattern to the underlying sample substrate. There are a number of problems in both SFIL and TNIL processes, including stencil durability, performance, imprint tolerances, and critical size control when transferring the pattern to the underlying substrate. The residual, unsealed layer that remains after the imprinting process requires an additional etching step to the main etching with transferring the pattern. The single-field NIL encounters difficulty in controlling the uniformity of the replicated pattern across a large surface area substrate, due to problems in maintaining uniform pressure over large areas. A step-by-step method with repetition can potentially cover large areas, but the microstructure formed at each step is independent of other steps, and the formation of a seamless micro- or nanostructure over a large area without combination is a problem. Alignment errors occur when misaligning repeated hyphenation patterns.

If you can get the surface of the roller with a uniformly applied pattern, there is the possibility of processing from roll to roll. Japanese Unexamined Patent Publication No. 59200419A, published November 13, 1984 under the title "Large Area Exposure Apparatus", by Toshio Aoki et al., Describes the use of a transparent cylindrical drum that can perform rotational and translational movement, with an internal light source and a printed pattern mask material attached to the outside of the cylindrical drum. Inside the drum there is a film of transparent heat-reflecting material. A substrate with an aluminum film on its surface and a photoresist deposited on top of the aluminum film contacts a photomask with a printed pattern on the surface of the drum, and the image forming light passes through the photomask to form an image in the photoresist on the surface of the aluminum film. Then, the photoresist appears to provide a printed photoresist. Then, the printed photoresist is used as an etching mask for the aluminum film present on the substrate.

There is no description regarding the types of materials that were used as the photomask film or photoresist on the surface of an aluminum film. To form an image in a photoresist deposited on top of an aluminum film, a high-pressure mercury tube light source (500 W) was used. Glass substrates with a thickness of about 210 mm (8.3 inches) × 150 mm (5.9 inches) and about 0.2 mm (0.008 inches) were created using a pattern transfer device with a cylindrical drum. The size of the pattern element transferred using such a technique was about 500 μm ² , which obviously is a square of about 22.2 μm × 22.2 μm in size. This element size was based on the approximate pixel size of the LCD display at the time of filing the patent application (1984). It was stated that the photomask film outside the cylindrical drum, as mentioned, withstands approximately 140,000 transfers of the pattern. The contact lithography scheme used by Toshio Aoki et al. Does not allow submicron elements to be created.

Tapio Makela et al. From VTT, a technical research center in Finland, published information on a custom-made, laboratory-to-roll roll-to-roll imprinting tool for manufacturing high-performance submicron structures. Hitachi and others developed a prototype sheet metal or roll-to-roll NIL, and demonstrated the ability to process sheets 15 meters long. The objective was to create a continuous imprint process using tape molding (nickel-plated molds) to imprint polystyrene sheets for applications with large geometry, such as fuel cell membranes, batteries, and possibly displays. Currently, prototype tools do not provide the desired performance. In addition, it is necessary to increase reliability and reproducibility with respect to the printed surface. Toshiba also published information on a roll-to-roll UV imprinting tool designed to create submicron sized elements.

The technique of nanoimprint lithography, including NIL from roll to roll, however, should solve a number of problems. Defects can occur due to incomplete filling of negative patterns and the drying phenomenon, which often occurs with respect to polymeric materials. The difference in thermal expansion coefficients between the mold and the substrate causes transverse stress, and the stress is concentrated in the corner of the figure. The voltage generates defects and leads to fault defects in the main part of the figure at the stage of mold release. In addition, the heterogeneity of the thickness of the residual, unprinted layer, which remains after the imprinting process, is especially harmful in relation to obtaining a uniformly etched pattern in a large area substrate under an imprinted resist layer.

Soft lithography is an alternative to photolithography as a method of micro- and nanoproduction. This technology relates to forming copies of self-assembled monolayers. In soft lithography, an elastomeric stamp with patterned relief structures on its surface is used to generate patterns and structures with element sizes ranging from 30 nm to 100 nm. The most promising soft lithography technique is microcontact printing (µCP) with self-assembled monolayers (SAM). The main µCP process includes: 1. A mold made of polydimethylsiloxane (PDMS) is immersed in a solution of a special material, and the special material is able to form a self-assembled monolayer (SAM). Such special materials can be called ink. A special material sticks to the protruding pattern on the surface of the PDMS master. 2. The PDMS mold with the surface coated with the material facing down is in contact with the surface of the substrate coated with a metal, for example gold or silver, so that only the pattern on the surface of the PDMS mold is in contact with the metal coated substrate. 3. The special material forms a chemical bond with the metal, so that only the special material located on the protruding surface of the pattern, still remains on the surface with a metal coating after removing the mold from PDMS. SAM forms a special material on a metal-coated substrate, which extends over the metal-coated surface by about one to two nanometers (just like ink on a sheet of paper). 4. The PDMS mold is removed from the metal-coated surface of the substrate, leaving the patterned SAM on the metal-coated surface.

The most acceptable special materials for the formation of SAM on surfaces coated with gold or silver are alkanethiolates. When the surface of the substrate contains substances ending with a hydroxyl group, for example, Si / SiO ₂ , Al / Al ₂ O ₃ , glass, mica, and plasma-treated polymers, it is convenient to use alkylsiloxanes as special materials. With respect to alkanethiolates, μCP of hexadecanthiol on evaporated thin films (10-200 nm thick) of gold or silver seems to be the most reproducible process. Although these are the most well-known materials for patterning, gold and silver are not compatible with microelectronic devices based on silicon technology, although electrodes or wires containing gold or silver can be used. Currently, µCP for SAM from siloxanes on Si / SiO ₂ surfaces is not as pliable as SAM from alkanethiolates on gold or silver. Siloxane SAMs on Si / SiO ₂ often provide random SAM and in some cases generate submonolayers or multilayers. Finally, the patterned molds available for µCP are flat “stamp” surfaces, and reproducible and reliable printing over large areas requires not only very precise alignment of the printed pattern from the mold, but also constant wetting of the stamp with special material forming SAM, which is very difficult.

Some new optical lithography techniques, based on extremely weak near-field effects, have already demonstrated the advantages of printing sub-100 nm structures, although only in small areas. Near-field phase shift lithography NFPSL provides exposure of the photoresist layer to ultraviolet (UV) light, which passes through the elastomeric phase mask while the mask is in conformal contact with the photoresist. Bringing the elastomeric phase mask into contact with a thin layer of photoresist causes the photoresist to "wet" the surface of the contact surface of the mask. The passage of UV light through a mask in contact with the photoresist exposes the photoresist to the light intensity distribution that develops on the surface of the mask. In the case of a mask with a depth of relief, which is designed to modulate the phase of transmitted light by π, a local zero intensity occurs at the edge of the step of the relief. When using a positive photoresist, exposure through such a mask, followed by development, gives a photoresist line whose width is equal to the characteristic width of zero in intensity. For light 365 nm (near UV) in combination with a traditional photoresist, the intensity zero width is about 100 nm. A PDMS mask can be used to form an atomic-scale conformal contact with a flat, solid layer of photoresist. This contact is established spontaneously upon contact, without pressure being applied. Generalized adhesion forces direct this process and provide a simple and convenient way to align the mask in angle and position in the direction normal to the photoresist surface to establish good contact. There is no physical gap with a photoresist. PDMS is transparent to UV light with wavelengths above 300 nm. The passage of light from a mercury lamp (the main spectral lines of which lie in the range 355–365 nm) through PDMS, which is in conformal contact with the photoresist layer, exposes the photoresist to the intensity distribution formed on the mask.

Yasuhisa Inao, in a presentation entitled "Near-Field Lithography as a prototype nano-fabrication tool" at the 32nd International Conference on Micro- and Nano-Technologies in 2006, described the near-field step-by-step nanolithography developed by Canon, Inc. Near Field Lithography (NFL) is used when the distance between the mask and the photoresist that the image is to be transferred to is as small as possible. The initial distance between the mask and the substrate plate was set to about 50 nm. The application technique was described as “processing a three-layer resist” using a very thin photoresist. The mask for transferring the pattern was attached to the bottom of the pressure chamber and pressed to ensure "good physical contact" between the mask and the surface of the plate. The mask "deformed in accordance with the plate." It was indicated that an initial distance of 50 μm between the mask and the plate allows the mask to be moved to another position for exposure and drawing a pattern on areas over 5 mm × 5 mm. The patterning system used i-linear (365 nm) radiation from a mercury lamp as a light source. This method of stepwise exposure allowed us to successfully apply a pattern to a 4-inch silicon wafer with structures less than 50 nm.

In an article entitled "Large-area patterning of 50 nm structures on flexible substrates using near-field 193 nm radiation", JVST B 21 (2002), pages 78-81, Kunz et al. Described the use of near-field lithography with a phase-shift mask for applying a nanoparticle on flexible sheets (polyimide films) using hard quartz glass masks and exposure in the far UV range. In a subsequent article entitled "Experimental and computational studies of phase shift lithography with binary elastomeric masks", JVST B 24 (2) (2006) on pages 828-835, Maria et al. Presented experimental studies and calculations of a phase-shifting photolithographic technique that uses binary elastomeric phase masks in conformal contact with photoresist layers. The work considers optimized masks formed by casting and curing prepolymers into elastomeric poly (dimethylsiloxane) on anisotropically etched single-crystal silicon structures on SiO ₂ / Si. The authors report the possibility of using a phase mask from PDMS to form elements in the resist, in the full relief geometry on the mask.

US Pat. No. 6,753,131 to Rogers et al., June 22, 2004, entitled "Transparent Elastomeric, Contact-Mode Photolithography Mask, Sensor, and Wavefront Engineering Element", describes a phase mask for contact photolithography, which includes a diffraction surface having many recesses and protrusions. The protrusions are brought into contact with the surface of the positive photoresist, and the surface is exposed to electromagnetic radiation through a phase-shifting mask. The phase shift due to the passage of radiation through the recesses as opposed to the protrusions is essentially complete. Thus, at the boundaries between the recesses and protrusions, minima of the intensity of electromagnetic radiation are formed. The elastomeric mask is in good agreement with the surface of the photoresist, and after developing the photoresist, details of less than 100 nm can be obtained. (Abstract). In one embodiment, the reflection plates are used outside of the substrate and the contact mask, whereby the radiation returns to the desired location with a phase shift. In another embodiment, the substrate can be shaped to deform the phase-shift mask, which affects the behavior of the phase-shift mask during exposure.

U.S. Patent Application No. U.S. 2006/0286488, Rogers et al., Published December 21, 2006, entitled "Methods And Devices For Fabricating Three-Dimensional Nanoscale Structures", describe methods for making 3D structures on substrate surfaces. 3D structures can be generated using a conformal elastomeric phase mask capable of conformal contact with radiation-sensitive material that undergoes photo-processing (to create 3D structures). 3D structures may not pass through all radiation sensitive material. (Abstract).

Surface Plasmon Near Field Lithography (NFSPL) uses near field excitation to induce photochemical or photophysical changes to create nanostructures. The main near-field technique is based on increasing the local field around metal nanostructures illuminated at the resonant frequency of the surface plasmon. Plasma printing consists of using a vanishing wave driven by plasmons through metal nanostructures to create photochemical and photophysical changes in the layer under the metal structure. In particular, the visible exposure (λ = 410 nm) of silver nanoparticles in close proximity to a thin film of a g-line photoresist (AZ-1813, available from AZ-Electronic Materials, MicroChemicals GmbH, Ulm, Germany) can create selective exposure regions with a diameter less than λ /twenty. W. Srituravanich et al. In an article entitled "Plasmonic Nanolithography", Nanoletters V4, N6 (2004), pp. 1085-1088, describe the use of near-UV light (λ = 230 nm - 350 nm) to excite SP on metal substrate, to increase transmission through periodic apertures of sub wavelength with effectively shorter wavelengths compared to the wavelength of the exciting light. A plasmon mask designed for lithography in the UV range consists of a layer of aluminum perforated with 2-dimensional periodic arrays of holes, and two surrounding layers of dielectric, one on each side. Aluminum is chosen because it can excite SP in the UV range. Quartz is used as a substrate to support the mask, with an intermediate layer of poly (methyl methacrylate), which acts as an adhesive for aluminum foil and as a dielectric between aluminum and quartz. Poly (methyl methacrylate) is used in combination with quartz because of its transparency to UV light at the exposure wavelength (i-line at 365 nm) and comparable dielectric constants (2.18 and 2.30 for quartz and PMMA, respectively). A pattern in the form of an array of dots with a size of less than 100 nm and a period of 170 nm was successfully generated using exposure radiation with a wavelength of 365 nm. Obviously, the full area of the drawing was about 5 μm × 5 μm, without any scalability problems discussed in this article.

It does not seem that the method of imprinting (with thermal or UV curing) or soft lithography using printing with SAM materials is a high-tech process. In general, the imprinting method creates deformation of the substrate material due to heat treatment (e.g., thermal NIL) or drying of the details of the pattern upon curing of the polymer (parts in a UV-curable polymer). Furthermore, due to the application of pressure (hard contact) between the die and the substrate, defects are essentially impossible to avoid, and the die has a very limited service life. Soft lithography has the advantage that it is a printing technology without heating and stresses. However, the use of SAM as an “ink” for a sub-100 nm pattern is very problematic due to the drift of molecules on the surface, and the applicability of this technology over large areas has not been experimentally confirmed.

SUMMARY OF THE INVENTION

Embodiments of the invention relate to methods and apparatus useful in applying nanoparticles to large area substrates ranging from about 200 mm ² to about 1,000,000 mm ² , by way of example, but not limitation. In some cases, the substrate may be a film that has a predetermined width and an indefinite length and is sold in rolls. The nanoscale drawing technique uses near-field UV photolithography, where the mask used to apply the substrate pattern is in dynamic contact or in close proximity (in an alternating field of damped vibrations, less than 100 nm) from the substrate. Near-field photolithography may include phase shift mask technology or surface plasmons. The element size obtained using the described methods varies from about 1 μm lower to about 1 nm, and often from about 100 nm to about 10 nm.

In one embodiment, the exposure device includes a phase shifting mask in the form of a UV transparent rotatable mask having a particular phase shifting relief on its outer surface. In another embodiment of the phase shift mask technology, the transparent rotatable mask, which is usually a cylinder, may have a polymer film, which is a phase shift mask, and the mask is attached to the outer surface of the cylinder. When it is difficult to achieve good and uniform contact with the surface of the substrate, especially for large processing areas, it is advantageous for the polymer film to be a conformal elastomeric polymer film, for example PMDS, which forms good conformal contact with the substrate due to the van der Waals forces. The phase-shifting mask of the polymer film may consist of multiple layers, where the outer layer has nanoparticles for a more accurate representation of the prescribed dimensions of the elements in the layer sensitive to radiation (photosensitive layer).

Another embodiment of the exposure device uses a soft elastomeric material of the photomask, for example, a PDMS film having manufactured opaque elements on one of its surfaces, which is attached to the outer surface of the cylinder. Such elements can be chrome parts created on a PDMS film using one of the lithography methods known in the art.

According to an embodiment of the exposure device, which includes surface plasmon technology, a metal layer or film is layered or deposited on the outer surface of the rotatable mask, which is usually a transparent cylinder. The metal layer or film has a special sequence of through nanoholes. In another embodiment of surface plasmon technology, a layer of metal nanoparticles is deposited on the outer surface of a transparent rotatable mask to achieve deposition of a nanoparticle improved by surface plasmons. A radiation source is provided inside the transparent cylinder. For example, but not limited to, a UV lamp may be installed inside the cylinder. Alternatively, the radiation source may be located outside the cylinder, with light from the radiation source transmitted through tubes into the cylinder through one or both ends of the cylinder. The radiation can be directed outside the cylinder or inside the cylinder to specific areas within the cylinder using an optical system that includes, for example, mirrors, lenses, or combinations thereof. The radiation present in the cylinder can be directed to the contact region of the mask substrate using an optical diffraction grating. The radiation can be directed to the mask substrate region (connected) through a diffraction grating waveguide. A waveguide or diffraction grating is usually located inside the cylinder to redirect radiation to the contact areas between the outer surface of the cylinder and the surface of the substrate on which the image is to be formed.

In a specialized embodiment of the radiation light source, an OLED flexible display can be attached around the outer surface of the rotatable mask to emit light from each of the pixels to the substrate. In this case, the rotating mask should not be transparent. In addition, the specific pattern transferred to the radiation sensitive material on the surface of the substrate can be generated depending on the application by controlling the light emitted from the acid. The portable drawing can be changed "on the go" without the need to stop the production line.

In order to ensure a high productivity of transferring the pattern to radiation sensitive material and to increase the area with the surface pattern applied, it is useful to move the substrate or a rotating mask, for example, a cylinder, relative to each other. The cylinder rotates on the surface of the substrate when the substrate is stationary, or the substrate moves to the cylinder when the cylinder is stationary. For the reasons discussed below, there are advantages to moving the substrate to the cylinder.

It is important to be able to adjust the magnitude of the force that occurs on the contact line between the cylinder and the radiation sensitive material on the surface of the substrate (for example, on the contact line between the printed elastomeric film present on the surface of the cylinder and the photoresist on the surface of the substrate). To control this contact line, the cylinder can be supported by a tensioner, for example, springs, which compensate for the weight of the cylinder. The substrate or cylinder (or both) moves (up and down) to each other, as a result of which the gap between the surfaces decreases until there is contact between the cylinder surface and the radiation sensitive material (for example, an elastomeric film with a printed pattern and a photoresist on substrate surface). The printed elastomeric film will create a bond with the photoresist by means of van der Waals forces. Then the position of the substrate moves back (down) to the position at which the springs are stretched, but the elastomeric film with the printed pattern remains in contact with the photoresist. Then, the substrate can be moved toward the cylinder, causing the cylinder to rotate, maintaining dynamic contact between the printed elastomeric film and the photoresist on the surface of the substrate. Alternatively, you can rotate the cylinder, and the substrate can move independently, but synchronously, which will guarantee contact without slipping during dynamic exposure.

Multiple cylinders can be combined into one system and placed for sequential exposure of the radiation-sensitive surface of the substrate to provide double, triple and multiple application of the pattern on the surface of the substrate. This exposure technique can be used to provide higher resolution. The relative positions of the cylinders can be adjusted using an interferometer and a suitable computerized control system.

In another embodiment, the exposure dose can affect the lithography, and therefore, edge lithography (where narrow parts corresponding to, for example, a phase shift in a PDMS mask can be formed) can be converted to traditional contact lithography, and the size of the part in photoresist, where the image is formed may be determined by the exposure dose. Such exposure dose control is possible by controlling the radiation source power or cylinder rotation speed (exposure time). The size of the element created in the photoresist can also be adjusted by changing the wavelength of the exposure radiation, for example, a light source.

Masks on the cylinders can be oriented in an angle to the direction of movement of the substrate. This allows you to form a pattern in different directions relative to the substrate. To provide 2D patterns, two or more cylinders may be arranged in series.

In another embodiment, the transparent cylindrical chamber does not have to be rigid, but can be formed from a flexible material in which the pressure of the optically transparent gas can be maintained. The mask may be a cylinder wall or conformal material present on the surface of the cylinder wall. This allows the cylinder to roll on a substrate that is not flat, providing conformal contact with the surface of the substrate.

Brief Description of the Drawings

How you can implement the illustrative embodiments of the present invention will be described in detail with reference to the above private description and with reference to the detailed description of illustrative embodiments that the applicants have provided with illustrative drawings. It is obvious that the drawings are provided only when it is necessary to understand illustrative embodiments of the invention, and that some well-known processes and devices are not illustrated here, so as not to obscure the inventive essence of the subject disclosure.

FIG. 1A is a cross-sectional view of one embodiment of a device 100 useful in applying a pattern to large areas of a substrate material, where the radiation-friendly cylinder 106 has a hollow interior 104 in which the radiation source 102 is located. In this embodiment, the outer surface 111 of the cylinder 106 has a pattern with a particular surface topography 112. Cylinder 106 rolls over radiation sensitive material 108 that lies on substrate 110.

FIG. 1B shows a top view of the device and substrate shown in FIG. 1A, where in the radiation sensitive material 108, an image 109 is formed by radiation (not shown) passing through the surface topography 112.

FIG. 2 shows a cross-sectional view of another embodiment of a device 200 useful in applying a pattern to large areas of a substrate material. 2, the substrate is a film 208 that depicts a pattern using radiation that passes through a surface topography 212 on the first (transparent) cylinder 206 while the film 208 moves from the bobbin 211 to the bobbin 213. A second cylinder 215 is provided on the back side 209 of the film 208 to control the contact between the film 208 and the first cylinder 206.

FIG. 3 is a cross-sectional view of another embodiment of a device 300 useful in applying a pattern to large areas of a substrate material. 3, the substrate is a film 308 that moves from a bobbin 311 to a bobbin 313. A first transparent cylinder 306 with a surface relief 312 is used to apply a pattern to the upper side 310 of the film 308, and a second transparent cylinder 326 with a surface relief 332 is used to drawing a pattern on the lower side 309 of the film 308.

FIG. 4A is a cross-sectional view of an embodiment 400 of a transparent cylinder 406 that includes a hollow central region 404 with an internal radiation source 402. The surface relief region 412 is a conformal structure that includes a polymer film 415 with a patterned surface 413, which is especially useful for near-field lithography.

FIG. 4B shows an enlarged view of a surface 413, which is a polymer surface relief structure 413 located on top of a polymer base material 415. According to FIG. 4B, the polymer base material 415 may be the same polymer material as the material of the patterned surface 413, or other polymeric material.

FIG. 5A is a cross-sectional view of an alternative embodiment 500 of surface topography 512 that is present on a hollow transparent cylinder 506.

FIG. 5B shows an enlarged surface relief 512, which is a thin metal layer 514, on which is printed a sequence of nanoholes 513, where a metal layer is deposited on the outer surface 511 of the hollow transparent cylinder 506.

FIG. 5C shows an alternative surface relief 522 that can be used on the surface of the transparent cylinder 506. The surface relief 522 is formed by metal particles 526 that can be applied directly to the outer surface 511 of the hollow transparent cylinder 506 or to a transparent film 524 that is attached to the outer the surface 511 of the hollow transparent cylinder 506.

6A is a schematic three-dimensional illustration 600 of a transparent cylinder 604 having a patterned surface 608, where the cylinder 604 is suspended over a substrate 610 using a tensioner 602, illustrated as springs.

6B schematically shows an embodiment 620, where the radiation used for imaging comes from a radiation source 612 outside the cylinder 604, the radiation being internally distributed 615 and 616 in the hollow portion of the cylinder 604.

6C schematically shows an embodiment 630 where the radiation used for imaging is supplied from an external radiation source 612, focused 617 into a waveguide 618, and distributed from the waveguide 618 to an optical diffraction grating 621 present on the inner surface 601 of the cylinder 604.

6D schematically shows an embodiment 640, where the radiation used for imaging is supplied from two external radiation sources 612A and 612B, and focuses 621 and 619, respectively, on an optical diffraction grating 621 present on the inner surface 601 of the cylinder 604 .

FIG. 7A is a schematic view showing the use of multiple cylinders, for example, two cylinders 702 and 704, for example, sequentially, to provide multiple printings that can be used, for example, to obtain a higher resolution.

FIG. 7B is a schematic sectional view showing the pattern 706 created by the first cylinder 702 after imaging and developing the radiation sensitive material 710. The modified pattern 708 is obtained after imaging and developing the radiation sensitive material 710, the modified pattern 708 being created using the first cylinder 702 in combination with the second cylinder 704.

FIG. 8 is a schematic cross-sectional view of a deformable cylinder 800, the interior of which 804 is pressurized using an optically transparent gas supply device 813. The outer surface 811 of the deformable cylinder 800 may be a nanostructured / nano-coated film 802 of conformable material that can be rolled on a non-planar substrate 805, which makes it possible to accurately apply radiation from a radiation source 802 to the surface 816 of the substrate 805.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Starting a detailed description, we note that the use of the names of the elements in the description of the invention and the claims in the singular does not exclude the presence of several such elements, unless the context clearly indicates otherwise.

The word “about” as used herein means that the nominal value is represented with an accuracy of ± 10%.

Embodiments of the invention relate to methods and apparatus useful in applying nanoparticles to large area substrates, where a rotatable mask is used to form an image in a radiation sensitive material. Usually a rotatable mask contains a cylinder. The nanoscale deposition technique uses near-field photolithography, where the wavelength of the radiation used to form the image in the radiation sensitive layer on the substrate is 438 nm or less, and where the mask used to apply the pattern to the substrate is in contact with the substrate. Near-field photolithography can use a phase-shift mask, or nanoparticles on the surface of a transparent rotating cylinder, or can use surface plasmon technology, where the metal layer on the surface of the rotating cylinder contains nanoholes. The following detailed description merely illustrates the possibilities that will become apparent to those skilled in the art upon reading this disclosure.

Although the rotating mask used to generate the nanoparticle in the layer of radiation-sensitive material can be of any useful configuration, and some of them are described below, a hollow cylinder is particularly preferred with respect to the production capabilities of an imaged substrate with minimal operating costs. FIG. 1A is a cross-sectional view of one embodiment of a device 100 useful in applying a pattern to large areas of a substrate material, where the radiation-friendly cylinder 106 has a hollow interior 104 in which the radiation source 102 is located. In this embodiment, the outer surface 111 of the cylinder 106 has a pattern with a particular surface topography 112. The cylinder 106 rolls along the radiation sensitive material 108, which lies on the substrate 110. FIG. 1B shows a top view of the device and the substrate shown in FIG. 1A, where an image 109 is formed by radiation in the radiation sensitive material 108 ( not shown) passing through surface topography 112. The cylinder rotates in the direction shown by arrow 118, and the radiation from the radiation source 102 passes through a nanoparticle 112, present on the outer surface 103 of the rotating cylinder 106, to form an image in the radiation sensitive layer (not shown) on the substrate 108, to provide the image Figure 109 in a layer sensitive to radiation. Then, a radiation sensitive layer is developed to provide a nanostructure on the surface of the substrate 108. FIG. 1B shows that the rotatable cylinder 106 and the substrate 120 are driven independently of each other. In another embodiment, the substrate 120 can be held in dynamic contact with the rotatable cylinder 106 and move toward or away from the contact surface of the rotatable cylinder 106 to provide movement to the stationary rotatable cylinder 106. In yet another embodiment, the rotatable cylinder 106 can be rotated on the substrate 120 while the substrate is stationary.

A particular surface topography 112 may be etched on the outer surface of the transparent rotating cylinder 106. Alternatively, a particular surface topography 112 may be present on a film of polymer material adhered to the outer surface of the rotating cylinder 106. A film of polymer material can be created by depositing the polymer material on a mold (master). A wizard created on a silicon substrate, for example, is usually generated using direct electron beam exposure of the pattern onto a photoresist present on the silicon substrate. Then the pattern is etched in a silicon substrate. The silicon master mold pattern is reproduced in a polymer material deposited on the mold surface. The polymer material is preferably a conformal material that exhibits sufficient rigidity to withstand wear when used as a mask in contact with the substrate, but which can also provide good contact with the radiation sensitive material on the surface of the substrate. One example of conformal materials commonly used as transfer masking material is PDMS, which can be cast on the surface of a master mold, cured with UV light and peeled off the mold to create a good copy of the mold surface.

FIG. 2 shows a sectional view 200 of another embodiment of a device 200 useful in applying a pattern to large areas of a substrate material. 2, the substrate is a film 208 that depicts a pattern using radiation that passes through a surface topography 212 on the first (transparent) cylinder 206 while the film 208 moves from the bobbin 211 to the bobbin 213. A second cylinder 215 is provided on the back side 209 of the film 208 to control the contact between the film 208 and the first cylinder 206. The radiation source 202 present in the hollow space 204 inside the transparent cylinder 206 may be a mercury lamp or other radiation source that provides emits a wavelength of 365 nm or less. The surface relief 212 may be a phase-shifting mask, for example, where the mask includes a diffraction surface having many recesses and protrusions, as discussed above in the section "prior art". The protrusions are brought into contact with the surface of a positive photoresist (radiation sensitive material), and the surface is exposed to electromagnetic radiation through a phase mask. The phase shift due to the passage of radiation through the recesses as opposed to the protrusions is essentially complete. Thus, at the boundaries between the recesses and protrusions, minima of the intensity of electromagnetic radiation are formed. The elastomeric phase mask agrees well with the surface of the photoresist, and after developing the photoresist, details of less than 100 nm can be obtained.

FIG. 3 shows a cross-sectional view 300 of another embodiment of a device 300 useful in applying a pattern to large areas of a substrate material. The substrate is a film 308 that moves from the bobbin 311 to the bobbin 313. A layer of radiation-sensitive material (not shown) is provided on both the upper side 310 of the film 308 and the lower side 309 of the film 308. A first transparent cylinder 306 is provided. with a hollow center 304, which includes a radiation source 302 having a surface topography 312 that is used to print on the upper side 310 of the film 308. A second transparent cylinder 326 is provided, with a hollow center 324 that includes a radiation source 32 2, having a surface relief 332, which is used to apply a pattern to the lower side 309 of the film 308.

FIG. 4A is a cross-sectional view 400 of an embodiment of a transparent cylinder 406 that includes a hollow central region 404 with an internal radiation source 402. The surface relief 412 is a conformal structure that includes a polymer film 415 with a patterned surface 413 that especially useful for near-field lithography. The polymeric material of the patterned surface 413 must be rigid enough so that the pattern contacts the surface of the substrate on which the image is formed in the proper place. At the same time, the polymeric material must be consistent with the surface of the radiation sensitive material (not shown) in which the image is formed.

FIG. 4B shows an enlarged view of a surface 413, which is a polymer surface relief structure 413 on top of the polymer base material 415. Referring to FIG. 4B, the polymer base material 415 may be the same polymer material as the patterned surface material 413, or another polymeric material. A transparent conformal material, such as silicone or PDMS, for example, can be used as the polymer film 415, in combination with a more rigid transparent overlying layer of material, such as PDMS with a different ratio of miscible components or, for example, PMMA polymethylmethacrylate. This provides a patterned surface 413, which avoids distortion of the elements after contact with a place on the radiation-sensitive surface of the substrate (not shown), while the polymer base material simultaneously provides matching with the surface of the substrate as a whole.

FIG. 5A is a cross-sectional view 500 of a transparent cylinder 506, with a hollow central region 504 including a radiation source 502, where surface 511 represents an alternative embodiment of surface relief 512. FIG. 5B shows an enlarged view of a surface relief 512, which is a thin metal layer 514, on which is printed a sequence of nanoholes 513, where the metal layer is present on the outer surface 511 of the hollow transparent cylinder 506. The metal layer may be a patterned layer adhered to the outer surface of the transparent cylinder 506. In the alternative, the metal layer may be deposited on the surface of the transparent cylinder by evaporation or spraying, or by another method, known in the art, and then can be sequentially etched or burned by a laser to provide a patterned metal outer surface 511. FIG. 5C shows an alternative surface relief 522 that can be used on the surface of a transparent cylinder 506. The surface relief 522 is formed by metal particles 526 that are applied on the outer surface 511 of the hollow transparent cylinder 506 or on a transparent film 524, which is attached to the outer surface 511 of the hollow transparent cylinder 506.

6A is a schematic three-dimensional illustration 600 of a transparent cylinder 604 having a patterned surface 608. A radiation source (not shown) is present in the interior of the transparent cylinder 604. The transparent cylinder 604 is suspended above the substrate 610 using a tensioner 602, which is shown as springs in Figure 600. A person skilled in the art will know several tensioners that can be used to ensure proper the amount of contact between the outer surface 608 of the transparent cylinder 604 and the surface of the substrate 610. In one embodiment of the method of using the device shown in f ig. 6A, the device is used to form an image in a radiation sensitive material (not shown) on a substrate 610, where the substrate 610 is a polymer film that can be fed into and removed from the rewinder system like that shown in FIG. 2. The transparent cylinder 604 is lowered to the substrate of the polymer film (or the substrate of the polymer film rises), until there is contact with the material sensitive to radiation. A polymer film, which is usually elastomeric, will form a bond based on the van der Waals force with the radiation sensitive material. Then, the transparent cylinder 604 may rise (or the polymer film substrate may fall) to a position where contact is maintained between the surface 608 of the transparent cylinder 604 and the surface of the radiation sensitive material, but the tension between the two surfaces is such that the force applied to the surface 608, is minimal. This allows the use of very small elements of the deposited nanoparticle on the surface 608 of the transparent cylinder 604. When the substrate 610 begins to move, the transparent cylinder 604 also moves, which causes the transparent cylinder 604 to rotate, maintaining dynamic contact between the radiation-sensitive material and the underlying substrate 610 from a polymer film. At any moment of dynamic exposure, the contact between the cylinder and the photosensitive layer is limited to one narrow line. Due to the significant van der Waals forces between the elastomeric film, for example, on the outer surface of the cylinder and the layer sensitive to radiation (photosensitive layer) on the substrate, the contact is kept uniform throughout the entire process and throughout the entire width (length) of the mask on the cylinder surface. In cases where the Van der Waals forces do not provide sufficiently strong adhesion between the contact surface of the cylinder and the photosensitive layer, a driving (rotating) cylinder can be used using a stepper motor synchronized with the translational motion of the substrate. This provides an exposure process without slipping for a polymer or other material of the surface of the cylinder, which does not provide large forces of adhesion to the substrate.

6B schematically shows an embodiment 620, where the radiation used for imaging is supplied from a radiation source 612 outside the cylinder 604, the radiation being internally distributed 615 and 616 in the hollow portion of the cylinder 604. The radiation can be directed through the transparent cylinder 604 through the patterned mask surface 608 to a radiation sensitive surface (not shown), substrate 608 using various lenses, mirrors, and combinations thereof.

6C schematically shows an embodiment 630 where the radiation used to form the image in the radiation sensitive material is supplied from a location outside the transparent cylinder 604. An external radiation source 612 is focused 617 into the waveguide 618 and distributed from the waveguide 618 to the optical diffraction a grid 620 present on the inner surface 601 of the cylinder 604.

6D schematically shows an embodiment 640, where the radiation used for imaging is supplied from two external radiation sources 612A and 612B, and focuses 621 and 619, respectively, on an optical diffraction grating 620 present on the inner surface 601 of the cylinder 604 .

FIG. 7A is a schematic view 700 illustrating the use of multiple cylinders, for example, two cylinders 702 and 704, for example, sequentially, to provide multiple printouts that can be used, for example, to obtain a higher resolution. The relative positions of the cylinders 702 and 704 can be controlled, for example, using data from an interferometer (not shown) in combination with a computerized control system (not shown).

7B is a schematic cross-sectional view 720 illustrating a pattern 706 created by a first cylinder 702 after imaging and developing a radiation sensitive material 710. The modified pattern 708 is obtained after imaging and developing the radiation sensitive material 710, the modified pattern 708 being created using the first cylinder 702 in combination with the second cylinder 704.

FIG. 8 is a schematic cross-sectional view of a deformable cylinder 800, the interior of which is pressurized 804 using an apparatus 813 that delivers an optically transparent gas, such as nitrogen. The outer surface 811 of the deformable cylinder 800 may be a nanostructured / nanoribbed film 812 of conformable material that can be rolled on a non-planar substrate 805, which makes it possible to accurately apply radiation from a radiation source 802 to the surface 816 of the substrate 805.

In another embodiment, a liquid having a refractive index greater than unity can be used between the surface of the cylinder and the material sensitive to radiation (for example, photosensitive) present on the surface of the substrate. You can, for example, use water. This increases the contrast of the elements of the picture in the photosensitive layer.

Although the invention has been described in detail for the various above embodiments, those skilled in the art can propose various modifications within the spirit and scope of the invention. Accordingly, the scope of the invention is defined by the attached claims.

Claims (30)

1. The method of near-field nanolithography, containing
a) providing a substrate having a radiation sensitive layer on the surface of said substrate,
b) providing a rotatable mask having a nanoparticle on the outer surface of said rotatable mask,
c) contacting said nanoparticle with said radiation sensitive layer on a surface of said substrate,
d) the distribution of radiation through said nanoparticle during rotation of said rotatable mask over said radiation sensitive layer, whereby an image having an element size in the range from less than 1 μm to about 1 nm in said radiation sensitive layer is created,
wherein said nanoparticle is capable of being a conformal nanoparticle that is consistent with said radiation sensitive layer on the surface of said substrate. 2. The method according to claim 1, in which said element size varies from about 100 nm to about 10 nm. 3. The method according to claim 1, wherein said radiation has a wavelength of 436 nm or less. 4. The method according to claim 1, in which said capable of being conformal nanoparticles is a molded or nanostructured polymer material. 5. The method according to claim 3, wherein said rotatable mask is a phase-shifting mask that causes the radiation to form an interference pattern in said radiation sensitive layer. 6. The method according to claim 3, in which said mask uses the behavior of surface plasmons. 7. The method according to claim 1, wherein said rotatable mask is a cylinder. 8. The method according to claim 7, in which said cylinder has a flexible wall, whereby said cylindrical shape can be deformed upon contact with the surface of said substrate. 9. The method of claim 8, wherein an optically transparent gas is used to fill said cylinder. 10. The method of claim 3, wherein said rotatable mask is a transparent cylinder, whereby radiation can be transmitted from a location inside said cylinder. 11. The method of claim 10, wherein said mask is a phase-shifting mask that is present as a relief on the surface of said transparent cylinder. 12. The method of claim 10, wherein said mask is a phase-shifting mask that is present on a layer deposited on the surface of said cylinder. 13. The method according to p. 12, in which said phase-shifting mask consists of multiple layers, and nanoparticles are made in the outer layer to more accurately represent the prescribed dimensions of the elements in said photosensitive layer. 14. The method according to claim 7, in which said substrate is held in dynamic contact with said rotatable cylinder and moves toward or away from the contact surface of said rotatable cylinder during radiation distribution from said contact surface of said cylinder. 15. The method according to claim 1, wherein said cylinder is rotated on said substrate when said substrate is stationary. 16. The method according to any one of claims 1 to 15, in which multiple rotating masks are in contact with the layer sensitive to radiation. 17. The method according to claim 1, in which said rotatable mask and the surface of said substrate move independently using a stepper motor and a motorized translational mechanism of the substrate, and in which the movement of said rotatable mask and the surface of said substrate are synchronized with each other, thereby achieving contact exposure without slipping of said radiation sensitive layer. 18. The method according to claim 1 or 17, further comprising using liquid at the interface between said rotatable mask and the surface of said substrate. 19. A device for implementing near-field lithography, containing
a) a rotatable mask having a nanoparticle on the outer surface of said mask; and
b) a radiation source that provides radiation with a wavelength of 436 nm or less from said nanoparticle while said nanoparticle is in contact with a radiation-sensitive layer of material,
wherein said nanoparticle is capable of being a conformal nanoparticle that is consistent with said radiation sensitive layer on the surface of said substrate. 20. The device according to claim 19, in which said rotatable mask is transparent. 21. The device according to claim 20, in which said rotatable mask is a phase-shifting mask. 22. The device according to claim 20, in which said rotatable mask uses radiation generated using surface plasmon methods. 23. The device according to item 21, in which the surface of the said mask contains a metal layer including nanoholes. 24. A device according to any one of claims 19-23, wherein said rotatable mask is a cylinder. 25. The device according to paragraph 24, in which said cylinder is a flexible cylinder. 26. The device according A.25, in which said flexible cylinder is filled with an optically transparent gas. 27. The device according to paragraph 24, in which multiple cylinders are present in the configuration, so that the said multiple cylinders sequentially pass on the substrate. 28. The device according to paragraph 24, in which there are multiple cylinders, and in which the cylinder is present both on the upper side and on the lower side of the substrate on which the said device creates an image. 29. The device according to p. 28, in which at least one cylinder that transmits radiation to form an image is present both on the upper side and on the lower side of the substrate on which the said device creates an image. 30. The device according to claim 19, in which the rotatable mask is suspended above the substrate using a tensioner that can be adjusted to control the amount of force applied to the surface in contact with the rotatable mask.

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