Photoresistless Lithography, Optical Processing Tools, and Methods Using VUV or Deep UV Lamps

Abstract

A manufacturing tool has an array of at least one flat light photon source or flat lamp, and the at least one flat light photon source is used to ablate polymer materials non-thermally from a surface. No photoresist is required, and the desired light ablation pattern is determined by inserting a lithographic organic mask between the lamp and the surface to be processed. The method of the present invention patterns organic polymers, and can use the pattern established in the organic polymer layer on the substrate to pattern the substrate, and can also deposit materials in the pattern by breaking the bonds in the deposition precursor with photons from a microplasma array. Another method transforms the organic polymer material into having a hydrophilic surface. The tool of the present invention can have a width and depth comparable to that of a typical paperback book and a height comparable to that of a coffee cup.

Description

[0001] Statement of Government Interest

[0002] This invention was made with government support under Air Force Office of Scientific Research grants No. FA9550-14-1-0002 and FA9550-18-1-0380. The government has certain rights in the invention.

[0003] Priority Claims and Incorporation by Reference of Related Applications

[0004] This application claims priority to U.S. Provisional Application No. 62 / 718,421, filed Aug. 14, 2018, and U.S. Provisional Application No. 62 / 746,797, filed Oct. 17, 2018, under 35 U.S.C. § 119 and all applicable statutes and treaties. Field of the Invention

[0005] The field of the present invention includes lithography and photoprocessing of thin films and bulk materials, including patterning, etching, and deposition of materials. Applications of the present invention include the design and manufacture of optical, semiconductor electronic, and biomedical devices and components, as well as integrated optical, electronic, and biomedical systems. Background of the Invention

[0006] Current semiconductor manufacturing processes for electronic and photonic devices are sequential in the sense that separate tools are typically required for each step (lithography, etching, deposition, “ashing,” etc.). For example, excimer lasers (ArF, KrF) steppers (step-and-repeat projection aligners) are commonly used tools for the lithography process, while typical tools for etching materials patterned by lithography are plasma systems.

[0007] During the complex manufacturing sequence of semiconductor electronic devices, which typically requires many lithography, etching, and film deposition steps, the transport of electronic devices between multiple tools not only slows down the manufacturing process but also greatly increases the manufacturing cost. The defect rate is also affected by repeated transfers between different tools. As the number of times an electronic device is transferred from one processing tool to the next increases, the likelihood of damaging the device on the wafer increases.

[0008] Nearly all existing lithography methods require the use of photoresist for defining patterns on a material surface to be processed by any of several micrometer- or nanometer-scale fabrication processes such as etching, thin film deposition, electroplating, and ashing. Fabrication of electronic and photonic devices generally requires multiple lithography steps during an overall processing sequence, and each of these steps requires: 1) uniformly applying a photoresist film to a surface; 2) exposing the photoresist to deep ultraviolet (UV) or vacuum ultraviolet (VUV) radiation (“light”) according to a predetermined pattern, and 3) removing the photoresist after completion of the desired surface processing (deposition, etching, etc.) of the surface and before proceeding to the next processing step. The latter requirement of removing the photoresist is typically accomplished by wet chemical methods using solvents. Accordingly, large volumes of solvents must be disposed of or recycled in an approved manner. In short, the requirement for photoresist at any step in the fabrication of photonic, electronic, or biomedical devices imposes financial and environmental burdens on manufacturers, consumers, and the public. Accordingly, it is desirable to eliminate one or more photoresists from the overall processing sequence.

[0009] Recent developments have provided thin, flat lamps that emit at 172 nm (and other wavelengths in the VUV [100 - 200 nm] and UV [200 - 400 nm] regions of the spectrum), which are now commercially available and generate intensities greater than 150 mW / cm 2 . In addition, these lamps supply efficiencies in excess of 20% “wall plug”. Several characteristics of these lamps have been described in “25W of Average Power at 172nm in the Vacuum Ultraviolet from Flat, Efficient Lamps Driven by Interlaced Arrays of Microcavity Plasmas”, S.-J. Park et al., APL Photonics, Vol. 2, 041302 (2017). Although lamps emitting at 172 nm have been in existence for decades, previous lamps were cylindrical and only produced low intensities (typically less than 50 mW / cm 2 ). Additionally, the flat form factor of these microplasma array-driven lamps allows them to be “tiled” mounted in a common frame, which, for example, allows for easy generation of spatially averaged intensities greater than 1 kW / m 2 uniformly and up to and exceeding 1 kW / cm 2The instantaneous (peak) intensity. On the other hand, cylindrical lamps or bulbs typically require VUV or UV optics located behind the lamp. Such optics are typically reflective and serve the following dual purposes: 1) capture the light emitted from the rear of the cylindrical lamp, and 2) direct as much of the lamp output as possible onto a flat surface for the purpose of illuminating the surface uniformly. Unfortunately, especially VUV reflective optics are expensive, degrade rapidly due to the formation of color centers (light absorption defects) in the reflector, and require alignment. If the coverage of the desired surface area is greater than the coverage accessible by a single lamp, then the radiation from adjacent parallel lamps needs to be overlapped in order to produce a uniform intensity over the entire surface. It should be mentioned that the phrase "deep UV" is used here to refer to the spectral region with radiation wavelengths between approximately 200 nm and 250 nm. As mentioned previously, the entire UV region is generally considered to cover the 200 - 400 nm region, and the VUV spectral region extends from 100 nm to 200 nm. Several flat lamps emitting at wavelengths greater than 250 nm will be mentioned here, but they all generate UV radiation.

[0010] In 2006, Asakura et al. [1] used 172 nm radiation that also illuminated the substrate to etch a PMMA film. Removing the film required an indoor air pressure of 1000 Pa (about 0.8 Torr) in the chamber for the process to occur. Thus, there was approximately 0.2 Torr of oxygen (O2) in the chamber, and it is well known that 172 nm photons have the ability to convert O2 into ozone (O3). Thus, as Asakura confirmed in the article, ozone was the cause of the authors' results (attributing the film etching to "reactive oxygen"). This severely limits the applicability of the process and does not allow multiple steps to occur in a single tool or continuous processing under vacuum.

[0011] References

[0012] [1] S. Asakura, A. Hozumi, T. Yamaguchi, and A. Fuwa, Thin Solid Films 500, 237 (2006).

[0013] [2] C. M. Papmeyer, M. Ott, K. Vissing, Langmuir 25, 7129 (2009).

[0014] [3] H. Sewell, D. McCafferty, and L. J. Markoya, U.S. Patent No. 7,684,014 (March 23, 2010)

[0015] [4]J.Gan,H.Chen,F.Zhou,H.Huang,J.Zheng,W.Song,L.Yuan,and Z.Wu,Colloids and Surfaces B:Biointerfaces 76,381(2010).

[0016] [5]A.C.Cefalas,E.Sarantopoulou,E.Gogolides,P.Argitis,Microelectronic Engr.53,123(2000).

[0017] [6]Y.Maezono,Y.Iwasa,M.Wasamoto1,I.Yamamoto,M.Katto,and A.iYokotani,Japan.J.Appl.Phys.47,7266(2008).

[0018] [7]K.Hamamoto,Y.Tanaka,T.Watanabe,N.Sakaya,M.Hosoya,T.Shoki,H.Hada,N.Hishinuma,H.Sugahara,and H.Kinoshita,J.Vac.Sci.Technol.B 23,247(2005).

[0019] [8]M.Yamaguchi,T.Wallow,Y.Yamada,R.-H.Kim,J.Kye,H.J.Levinson, "A Study of Photoresist Pattern Freezing for Double Imaging using 172nm VUV Flood Exposure", Proc. 25th Int. Conf. Photopolymer Sci. Technol. (ICPST-25, 2008).

[0020] [9]J.G.Eden, Photochemical Vapor Deposition (Wiley & Sons, 1992). Summary of the Invention

[0021] The preferred embodiment fabrication tool has an array of at least one flat light source or flat lamps for non-thermal ablation of polymeric materials from a surface. No photoresist is required, and the desired pattern of photoablation is determined by inserting a photolithographic mask between the (multiple) lamps and the surface to be processed. A contact mask or projection system can be employed, and optical components (such as Fresnel lenses, gratings, and phase masks) can be fabricated directly into polymeric films, sheets, or bulk materials. By using one or more masks and performing multiple exposures on the polymeric surface, complex and multi-layered networks with nanoscale features suitable for electronic, photonic, or biomedical applications are optically fabricated into any of a variety of polymers. By overcoating the pattern formed in the polymer and subsequently removing the underlying polymer by wet chemical or dry etching methods, the pattern fabricated into a polymeric film or thin layer can be replicated into metals, ceramics, or other materials. Hydrophilic polymeric surfaces are fabricated by these processes, allowing for the production of anti-fog (non-scattering) surfaces on the surfaces of glasses, goggles, and camera lenses. Watermarks and other information can be "encoded" into the polymeric film and can only be "read" by processing with a liquid such as acetone or alcohol. Multiple processes (including lithography, film etching, or deposition) on semiconductors or other materials can be accomplished in the same processing chamber without the need for photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic (cross-section, not to scale) of a preferred embodiment fabrication tool having an array of flat lamps, UV / UV photon sources, or flat lamps as photon sources that irradiate a wafer or other substrate through a photomask;

[0023] Figure 2 provides data related to the removal of a PMMA film (on Si) by a 172 nm (Xe2) lamp generating an intensity of 100 mW / cm 2 at the surface of the lamp during the experiments of the present invention;

[0024] Figures 3A to 3E is a SEM image of a pattern formed in an acrylic film during the experiments of the present invention by irradiating the acrylic film with a 172 nm flat lamp through a photomask;

[0025] Figure 4A and 4B are additional SEM images of a pattern formed in an acrylic film during the experiments of the present invention by irradiating the acrylic film with a 172 nm flat lamp through a photomask;

[0026] Figure 5 is a pseudo-color image (rendered in grayscale) of a 3D periodic nanoscale network fabricated in PMMA by a two-exposure process of the preferred embodiment;

[0027] Figure 6 is a pseudo-color image (rendered in grayscale) of another nano-scale network that has been fabricated through the two-step exposure process of the preferred embodiment;

[0028] Figure 7 is a pseudo-color image (rendered in grayscale) of the "spider web" structure according to the process of the preferred embodiment, which is fabricated using two different masks and sequential exposure of the PMMA surface.

[0029] Figure 8A and Figure 8B are a top perspective view and a bottom perspective view, respectively, of a preferred square light source for the manufacturing tool of the present invention;

[0030] Figure 9A and Figure 9B is a partial view of a preferred embodiment of a flat light source installed in the manufacturing tool of the present invention, including details for supplying power to the flat light source;

[0031] Figures 10A to 10C is a diagram of a preferred embodiment of a vertically stacked flat light source for the manufacturing tool of the present invention, including details for supplying power to the flat light source;

[0032] Figures 11A to 14H is a schematic diagram of a preferred embodiment of a flat light source in the form of a dome for the manufacturing tool of the present invention;

[0033] Figures 15A to 18M is a diagram of a preferred embodiment of a radial light source for the manufacturing tool of the present invention;

[0034] Figures 19A - 19D is a diagram illustrating roll-to-roll manufacturing according to the preferred method of the present invention;

[0035] Figure 20 is a schematic diagram (cross-section) of a two-chamber preferred embodiment manufacturing tool, where a micro-plasma lamp in one chamber drives processes such as lithography, thin film etching, or deposition in the second chamber;

[0036] Figure 21 is a diagram of an optical arrangement for directing the radiation of two flat light sources towards a substrate for the manufacturing tool of the present invention;

[0037] Figure 22 is a diagram of an optical arrangement for directing the radiation of multiple flat light sources towards a substrate for the manufacturing tool of the present invention;

[0038] Figure 23A and 23BIs an exploded view and perspective view of a preferred compact manufacturing tool of the present invention, which is well-suited for laboratory and small industrial applications;

[0039] Figure 24 Is a schematic diagram (cross-section) of a preferred embodiment manufacturing tool, where the photomask and the wafer (substrate) are close to the lower surface of the system for N2 flow ("spray") on the wafer during exposure for drying;

[0040] Figure 25 and Figure 26 Illustrates the effect of optically treating polymer microspheres using a preferred embodiment manufacturing tool to shrink the microspheres with 172 nm illumination. This "microsphere rarefaction" process is completely unexpected because despite the fact that the 172 nm radiation impinges on the array from one direction, the radiation also uniformly photoablates these spheres. That is, the microspheres remain spherical after radiation;

[0041] Figure 27 Is an exploded perspective view of a preferred embodiment manufacturing tool for a VUV or UV lithography system, where an array of polymer microspheres is used to fabricate optical components and systems.

[0042] Figure 28A and Figure 28B Shows two photographs of an optical system for viewing an image in the presence of water vapor ("fog") from hot water in a cup. In Figure 28A , the inclined polymer plate in the imaging beam path has been irradiated with a 172 nm lamp for 30 seconds, so that the surface of the polymer plate facing the water vapor is hydrophilic. In Figure 28B , the plate has not been VUV irradiated, and the image is completely blurred due to condensation of water droplets on the plate. Detailed Description

[0043] The manufacturing tool and manufacturing method of the present invention combine lithography and material photoablation (removal) in a single chamber (tool). There is no need to transfer between processing tools that perform multiple lithography and material removal or deposition steps. The preferred manufacturing tool utilizes an efficient flat vacuum ultraviolet (VUV) / ultraviolet (UV) lamp to perform two or more manufacturing processes in the same chamber (tool), which is expected to significantly reduce the cost of manufacturing electronic devices.

[0044] Preferred fabrication tools and methods also provide a lithography process that does not require chemical processing of photoresist in separate tools or by wet chemical processing. The preferred tools and methods reduce the cost of lithography, and a wider user community (primarily universities and small companies) has access to lithography with sub-200 nm resolution. The wider access to sub-200 nm lithography is a result of significantly reduced tool costs compared to the commercial processes and lithography systems currently used by large commercial semiconductor manufacturers of microprocessors, DRAMs, and other electronic "chips".

[0045] Preferred fabrication tools and methods use a flat lamp as a photon source during lithography. The flat lamp photon source can be adjacent to or within the processing chamber. This is not currently possible in the case of laser or XUV lithography. Additionally, the cost of the flat lamp photon source is at least an order of magnitude lower than the cost of existing laser photon sources most commonly employed in commercial fabrication processes. When the flat lamp photon source is integrated into or adjacent to the processing chamber (separated only by a VUV / UV transmissive window), the function provided by the lamp depends only on the wavelength(s) of the lamp and the combination of gases and vapors introduced into the chamber. For example, introducing carbon tetrachloride (CCl4) vapor into the chamber will cause the lamp radiation to photodissociate the molecules in order to produce chlorine (Cl) atoms, which will etch the exposed portion of the semiconductor wafer (substrate). Introducing other precursors into the chamber creates different processes. For example, illumination of trimethylaluminum (TMA) vapor with a lamp emitting at wavelengths below about 220 nm results in the deposition of aluminum atoms onto the exposed portion of the wafer. Importantly, the preferred fabrication tools and methods alter the conventional lithography process for fabricating microelectronic and nanoelectronic devices by enabling etching and deposition to be performed using the same tool in the same chamber.

[0046] Preferred fabrication tools and methods use a flat microplasma-driven lamp as a photon source during lithography, and the lamp configuration system supplies different arrangements of individual square or other geometric-shaped microplasma lamps in order to provide large-area uniform illumination on a semiconductor wafer or any flat surface. These arrangements, which include a "dome" configuration, can be used in combination with a roll-to-roll process developed for exposing low-cost substrates (such as acrylic films) on a paper backing. The present invention also provides a system having lamps that emit at one of two or three different wavelengths. The lamps are arranged to have alternating wavelengths, thereby allowing the surface to be uniformly illuminated by each of the two or three wavelengths for the purpose of selectively controlling the photochemistry in the tool. As an example, etching and deposition can occur simultaneously (or can be alternated in time) in the same tool.

[0047] The resolution of the present fabrication tools and methods is limited by the available wavelengths of flat lamps. Thus, the resolution currently provided by the present fabrication tools and methods is not as good as the highest spatial resolution currently available. For example, manufacturers such as Intel and AMD routinely build electronic products with feature sizes less than 20 nm. However, the currently available wavelengths allow for process integration, which allows for a significant reduction in process cost. Additionally, many lithographies do not require the highest available spatial resolution. For example, in the fabrication of electronics for flat TVs, the ability to pattern over large areas is important and does not require the highest resolution (although current processes exceed the resolution currently available for such applications). A resolution of sub-200 nm is a valuable process node that can now be achieved using inexpensive lamp arrays, and the present invention provides a method of combining lithography, deposition, and etching.

[0048] In the fabrication tools and methods of the present invention, suitable flat lamps for photon sources include the novel 172 nm emitting lamps discussed in the background art and described in "25W of Average Power at 172nm in the Vacuum Ultraviolet from Flat, Efficient Lamps Driven by Interlaced Arrays of Microcavity Plasmas", S.-J. Park et al., APL Photonics, Vol. 2, 041302 (2017). The wavelength of this VUV radiation corresponds to a photon energy of 7.2 eV, which the inventors have recognized can break most chemical bonds, including those required to effect material removal in semiconductor fabrication processes. More recently, flat lamps emitting at 126 nm, 147 nm, 222 nm, 240 - 260 nm, and 308 nm have also been demonstrated, but the currently available output power and efficiency of these lamps are currently lower than those available at 172 nm. Experiments using 172 nm lamps have confirmed that lithography methods and tools can directly form any desired pattern into thin films or sheets (or even bulk materials) of polymers such as, poly(methyl methacrylate) (PMMA), polycarbonate, ABS (acrylonitrile butadiene styrene), CR 39 (diethylene glycol bis(allyl carbonate)), PET (polyethylene terephthalate), polystyrene, and other materials. The resolution of this process has been demonstrated to be better than 150 nm and is suitable for roll-to-roll processing, which, to our knowledge, has previously been impossible at spatial resolutions of sub-200 nm.

[0049] Preferred fabrication tools and methods can also be used to directly fabricate optical and biomedical components (such as gratings, Fresnel lenses, phase masks, waveguides, other optical components, and arrays of microfluidic channels), as well as other biomedical and microfluidic components and devices, into polymers. Such components can be produced directly and inexpensively as acrylic (and other polymer) films, plates, or sheets, or even bulk materials. Such components can form the basis for extremely compact optical spectrometers, imaging systems, and even decorative items or "watermarks" on various surfaces. For the latter, watermarks and other information can be encoded into polymer films and sheets (such as those in which different forms of product and personal identification are sealed), and "read" only by treating the polymer with a liquid such as acetone or alcohol. The information is invisible by optical techniques such as microscopy.

[0050] It is well known that PMMA is a photoresist for electron beam (e-beam) lithography. Electron beam lithography is a maskless technique that allows a resolution of 10 nm. It is a slow technique due to the fact that the electron beam rasterizes the surface and must "expose" each feature individually. Thus, the 172 nm lithography technique described here can be used in combination with electron beam lithography in an effort to speed up the lithography process. Thus, during a first fabrication step, the 172 nm and electron beam lithography processes can be used to focus on features >200 nm. The sample is then loaded into an electron beam lithography tool, and in a second step, the electron beam is used to produce only the small features. Such a hybrid technique will allow (at least by an order of magnitude) a reduction in the cost and time required to fabricate large and small features in a single PMMA film.

[0051] Such components and devices can also be fabricated in metals, ceramics, or other materials by coating a pattern on the polymer surface with the desired material and subsequently removing the underlying polymer with a solvent (wet chemical method) or by dry etching.

[0052] Irradiation of polymers with VUV radiation renders the polymer surface hydrophilic, which in turn allows for the implementation of a variety of anti-fog surfaces. For example, the surfaces of automotive windshields, goggles, glasses, and camera lenses can now be treated with VUV radiation so as to remain transparent in the face of fog, rain, or spray in a marine environment.

[0053] Preferred embodiments of the present invention will now be discussed with reference to the drawings and experiments used to demonstrate the invention. The drawings may contain schematic representations that will be understood by those skilled in the art in light of the common general knowledge in the field and the subsequent description. For emphasis, features may be enlarged in the drawings and features may not be drawn to scale.

[0054] Figure 1FIG. 0 is a cross-sectional view of a preferred embodiment of a fabrication tool 10 of the present invention, showing a flat thin lamp or lamp array 12 in chamber 14 that emits in the VUV or UV region of the spectrum (nominal 100 - 400 nm) and irradiates the surface of semiconductor wafer 18 or other surfaces of a thin film that has been coated with a polymer through mask 16. Mask 16 may be in direct contact with substrate 18 or located near substrate 18. Alternatively, a mask not near the wafer surface may be used to project a desired pattern onto the surface of wafer 18. Figure 1 The position of mask 16 in Figure 1 is determined by the characteristics of the mask, the wavelength of lamp or lamp array 12, and the desired resolution on the wafer surface. Depending on the process to be performed, a gas or vapor or a mixture thereof may flow through inlet 20 into chamber at a gas pressure and flow rate electronically controlled by valves and mass flow controllers (not shown). If the desired process is lithography, chamber 14 may be evacuated to a base pressure typically less than 10 -6 Torr by vacuum system 22 (usually including a turbomolecular pump). However, it is generally advantageous to allow an inert (buffer) gas to slowly flow through the chamber for cooling the front surface(s) of the lamp(s). For a lithography process, the buffer gas should not absorb significantly at the wavelength of the lamp. Thus, for a lamp wavelength of 172 nm (emitted by Xe2 molecules), dry nitrogen, He, Ne, and Ar are suitable gases, but nitrogen is preferred because of its low cost. At shorter lamp wavelengths (such as 126 nm or 147 nm from Ar2 and Kr2, respectively), helium is the preferred choice, not only because of helium's high thermal conductivity and transmission down to the lower limit of the VUV region, but also because helium can be recycled and "scrubbed" cryogenically to minimize cost.

[0055] To perform a lithography process with a VUV / UV lamp according to a preferred method, first a wafer or other substrate 18 is spin-coated with a thin film of acrylic polymer PMMA (polymethyl methacrylate) or other organic polymer. A variety of organic polymer materials have been shown to function well for the applications described herein, including polycarbonate, ABS (acrylonitrile butadiene styrene), CR 39 (diethylene glycol bis allyl carbonate), PET (polyethylene terephthalate), and polystyrene. Most early experiments were performed using PMMA films with a thickness of 15 - 200 nm, but if the lamp intensity is higher than a few tens of mW / cm 2 , the range may be wider. The VUV photons generated by the lamp directly irradiate such a polymer film (or thin sheet or even bulk material) to non-thermally ablate the film at a rate that depends on the lamp intensity (i.e., photon arrival rate). For example, a 25-nm thick PMMA film is ablated by irradiating it with a 172-nm lamp having an intensity of 100 mW / cm 2 to obtain Figure 2Measurement values. The lamp manufactured by Eden Park Illumination is square (4” x 4” or 10cm x 10cm) and has a thickness of 3.8mm. The lamp can be installed inside or outside the lithography chamber, where the window is integrated into the chamber to allow VUV radiation to enter.

[0056] Polymer photoablation data

[0057] Figure 2 The importance of the data is that the PMMA film can be patterned without the need for photoresist. Also, no auxiliary gas (such as O2 for ozone generation) is required during the material removal process, and lithography can be performed over a wide range of chamber pressures. Thus, lamp 12 (in combination with the polymer film) serves to simultaneously create the desired pattern in the film and also physically remove the unwanted portions (regions) of the acrylic film. This process is called photoablation and is significant because experiments have shown that the process results in very little heating of the substrate. This is a huge advantage for lithography because there is no need to remove the semiconductor wafer from the processing chamber in order to process the wafer using solvents or to etch the wafer using plasma tools. Instead, the portion of the PMMA film exposed to the incident radiation is photoablated by 172nm photons. That is, the photon energy of 7.2eV (for the wavelength of the 172nm lamp) is large enough to break the chemical bonds in the PMMA film, resulting in the release of molecular fragments into the processing chamber 14. Another way of putting it is that the VUV (non-thermally) “evaporates” the portion of the PMMA thin film that is exposed to the lamp by the photomask. This type of process could not be observed with previous optical light sources. Photoablation of polymers has been observed with ArF (argon fluoride, 193nm) excimer laser radiation, and for example the success of such 193nm lasers in eye surgery called LASIK has been attributed to the synergistic effect of the high peak intensity of this pulsed laser with the photon energy (6.43eV at 193nm). However, in the process reported here, for example, the peak intensity of a 172nm lamp (less than 1kW / cm 2 ) is more than three orders of magnitude lower than the peak intensity of an excimer laser (MW / cm 2 in magnitude). Therefore, photoablation of polymer films with the peak VUV intensity available at 172nm (or other wavelengths) using a lamp is unexpected.

[0058] Accordingly, the processes disclosed herein are also quite different from conventional methods where the chemical structure of a photoresist is altered by incident ultraviolet radiation, but the photoresist material is not removed by an optical source (laser or ultraviolet lamp). An additional process (wet or dry etching of the irradiated or non-irradiated photoresist) is typically necessary to define the desired pattern. In other words, the combination of 172 nm radiation and a suitable (multiple) polymer film allows the direct and immediate generation of the desired lithographic pattern. Separate development and film removal processes are not required or desired. Wavelengths of other lamps in the 160 - 200 nm wavelength range will also prove to be effective. Wavelengths shorter than 160 nm may also be effective but have not been explored because the purge gas nitrogen begins to absorb significantly in that wavelength region.

[0059] Figure 2 The data shows that the ablation rate of the polymer film is initially linear during the time the film is exposed to the lamp radiation. However, for exposure times greater than about 15 s (for a lamp intensity of 100 mW / cm 2 ), the ablation rate shows signs of saturation. This non-linear behavior of the photoablation process can be utilized to achieve complex nano-scale structures through multiple exposures of the polymer film surface.

[0060] In addition to photoablation, the photochemical modification (photomodification) of non-ablated (but exposed) regions of certain polymers is performed, enabling the easy removal of the photomodified layer by rinsing with IPA, acetone, or other solvents. Although most polymers do not require this step, it can optionally be used to increase the depth of the photoablation structure.

[0061] Representative patterns, complex structures through multi-step exposure

[0062] Figures 3A to 3E and Figures 4A to 4B show various patterns generated in a PMMA film by irradiating the film through a photomask in a chamber similar to that shown in Figure 1 . For these tests, a 25 nm thick PMMA film was spin-coated onto a silicon (Si) substrate and then placed in a vacuum chamber that had a lamp mounted directly outside the chamber. The base pressure in the chamber was less than 10 -7However, this lithography process can function well even in a chamber with 1 atmosphere of gas (such as N2). This is a huge manufacturing advantage because there is no need to evacuate the processing chamber to a low reference pressure, but nitrogen or noble gas can be used to thoroughly flush the initial chamber air inside. The MgF2 window allows 172 nm photons to enter the chamber and irradiate the film in the area defined by the mask. After irradiating the film for 20 seconds, the film is removed (by non-thermal photoablation). Examination of the resulting pattern with an electron microscope (SEM) shows that the resolution of this lithography process is better than 150 nm, but additional tests are expected to provide a lower limit.

[0063] It must also be emphasized that the above lithography process is completely different from the lithography processes reported by Asakura et al. [1] in 2006 and discussed in the background art. This method does not require ozone to remove. Indeed, using ozone or other chemicals to remove surface materials may be counterproductive because it can well remove materials outside the pre-determined (desired) areas on the substrate surface. For the experiments conducted so far, only a rough pump is used to evacuate the chamber containing the lamp and the Si substrate coated with PMMA to a pressure below 0.5 Torr, and then it is backfilled with dry N2. Before exposing the PMMA film, this process is repeated at least 3 times. We conclude that the results in Figures 3 and 4 are due to the ablation of only the part of the PMMA film surface exposed to the lamp by 172 nm photons in a non-thermal manner. It should be reiterated that after using the pattern established by the ablation layer for further processing, this dry lithography process allows the mask and the substrate to remain in the processing chamber. Indeed, one can immediately proceed to the next process without "breaking the vacuum" in the chamber.

[0064] Figure 5 is a figure of the morphology of the nanostructure formed in the PMMA film by double-exposing the polymer film to a light source, presented in grayscale but originally in pseudo-color. Specifically, Figure 5 The 3D structure is fabricated by two consecutive exposures of the polymer surface interspersed with solvent rinses. The steps are as follows. First, the PMMA film is exposed to a 172 nm lamp (with an intensity of 100 mW / cm 2 ) for 25 seconds through a mask in the form of a periodic grating with 5 μm features. Then the surface is rinsed in isopropyl alcohol (IPA) for 4 seconds and in deionized (DI) water for 4 seconds. Then the photomask is rotated 90 degrees, and then the same exposure and rinse processes are repeated. The result is an array of 5 μm square features with depths of 320 nm and 640 nm and steep sidewalls. This surface pattern can then be replicated into metal or ceramic materials, for example, by covering with the desired material of the desired thickness Figure 5A polymer pattern (or any other pattern), and then the polymer is removed on the "back side" by wet chemical or dry etching. That is to say, the polymer patterning process can be used to form a molded part or template for further processing. It must be emphasized that surface patterns can be easily generated in polymers, metals, ceramics, and other materials that are difficult to fabricate by other techniques.

[0065] Figure 6 Another example is that micron- and nanoscale feature networks can be fabricated into the polymer surface by direct polymer ablation using a VUV lamp passing through one or more masks. This particular network is fabricated by the same process as Figure 5 which requires rotating a single mask.

[0066] Figure 7 is a grayscale image (originally pseudo-color) of a "spider web" structure, which is also fabricated by two consecutive exposures of the polymer surface. However, in this instance, two different masks are used, and the steps are as follows. First, the surface is exposed for 25 seconds using a lamp with an intensity of 100 mW / cm 2 passing through the mask. Then, the first mask is replaced with a second mask with a different pattern, and the surface is exposed again for 25 seconds with the same lamp intensity. After that, the surface is rinsed in IPA for 4 seconds and then rinsed in deionized water for 4 seconds. What is obtained is a structure with smoothed features by the second exposure. Such a process is suitable for fabricating sinusoidal and variable pitch ("chirped") gratings, as well as gratings for high-power femtosecond lasers (after transferring the polymer pattern into metal).

[0067] Multiple mask processes can also be employed to fabricate components and devices made of metal, ceramic, or other materials, where the surface pattern of the other material is inverted (i.e., "mirrored") from the pattern of the processed polymer surface. That is to say, people first fabricate the inversion of the desired pattern into the polymer surface. Therefore, after depositing ceramic, metal, or other materials onto the polymer surface and then removing the polymer itself, the metal or ceramic surface exposed by removing the polymer will be a mirror image of the metal or ceramic surface imprinted onto the polymer surface by VUV radiation.

[0068] The geometry of the photon-flat lamp "dome" and other lamp groups

[0069] In the manufacturing tool of the preferred embodiment, the UV / VUV radiation source is a flat lamp or an array of lamps. If needed, flat lamps driven by an array of microplasmas (described by S.-J. Park et al., APL Photonics, Vol. 2, 041302 (2017)) can be "tiled" and installed in a frame so as to be over 1 m 2Implement a strong VUV and / or UV radiation source over the area of... Figures 8A to 8B and Figures 9A to 9B is a diagram of an embodiment of a flat lamp frame that provides electrodes, electrode contacts, and dielectric spacers.

[0070] Figure 8A and Figure 8B Shows that the top side includes an electrode plate 52, and the bottom side includes a bottom grid 54, which serves as a frame for mounting a plurality of square plasma flat lamps 56. The grid 54 also includes lamp electrodes 58 to power the square micro-plasma flat lamps 56.

[0071] Figure 8B The bottom view shows that inserting the lamp 58 into the grid frame 54 naturally creates a physical "seam" in the structure. However, the diffraction of VUV / UV radiation when propagating away from the grid frame 54 will "fill" the intensity distribution when maintaining an appropriate distance from the surface to be irradiated. Depending on the application, this distance can vary from less than 2 mm to more than a few cm. That is, for various applications, the allowable variation in lamp intensity above the processed surface is different.

[0072] Figure 9A and 9B Illustrates additional details of the preferred embodiment. In the intersection region of the parts of the grid frame 54, the bottom contact 62 contacts the first (bottom) electrode 64 of each of the four lamps 56 (one is omitted in the figure to show other details). The dielectric spacer 66 electrically insulates the grid 54 from the top electrode contact region 68. The top electrode contact region contacts the second (top) electrode 70 of each of the four lamps 56.

[0073] Another lamp geometry is shown in Figures 10 and 11. The housing 72 includes an access door 74, such as the one shown, that slides out of a slot defined in the housing 72. The lamps 56 are mounted vertically on internal slots or rails 82 and contact two separate shared bus rail electrodes 76. The rail electrodes 76 include a top electrode rail 84 and a bottom electrode rail 86 having interleaved contact portions 84a and 86a that contact separate first and second electrodes of each lamp via electrical connectors 88. To deliver greater intensity than is available from a single lamp, the lamps 56 are simply arranged in a vertical stack within the housing 72. To achieve this goal, the front and back faces of the individual lamps typically lack reflective surfaces (other than those dictated by standard Fresnel reflection), and radiation provided by one lamp simply passes through the other lamps in the stack and exits the housing 72, which has no bottom or window to allow the combined emission from the stacked lamps 56 to pass through. The interior of the housing preferably contains a reflective surface 90 to redirect the transmission toward the target. The advantage of this geometry is that the transmission provided by multiple flat lamps is combined to increase the total radiation output. A disadvantage of this embodiment is that the transmission coefficient of each lamp is nominally 60-85%, depending on the lamp design. Therefore, the further the lamp is from the exit plane of the array, the less radiation will actually reach the surface to be treated. However, the geometry of Figures 10 and 11 is inexpensive to manufacture and maintain because the individual lamps can be slid horizontally out of the array and easily replaced, if desired.

[0074] Figures 12A to 13B is a diagram of a spherical or "dome" geometry for arranging lamps so as to increase and homogenize the spatial distribution of the VUV / UV radiation intensity reaching the surface to be illuminated. Figures 12A to 12B The arrangement is designed to utilize a single flat lamp of a given size (such as a square or rectangle). The grid frame 94 is arranged in a manner similar to Figure 8B The grid frame 54 shown in FIG. 5 is constructed in a comparable manner and is capable of accommodating a plurality of flat lamps 96. The grid 94 contains electrodes for supplying power to one electrode of each lamp. Each lamp has a contact 98 for receiving power from its other electrode. The combined emission of the lamps in the dome structure exits through a flat surface (emission aperture 99) at the base of the dome.

[0075] The geometry contains an overlap of lights at several different positions, but this is insignificant for achieving a uniform intensity profile under the dome, as indicated by Figure 12A and 12B As shown by the emission arrows in (where the surface to be illuminated or treated is located in the plane below the dome). Figure 13A and Figure 13Bshows a similar geometry that avoids the overlap of the intensity spatial profiles of individual lamps by having triangular spaces 102 that lack flat panel lamps. The spaces can be unoccupied or, as shown in Figures 12A to 12B , the spaces are capable of accommodating panels with reflective surfaces in order to direct VUV / UV radiation towards the bottom of the aperture ( Figure 13A ).

[0076] Figures 14A to 14H shows several different embodiments of a dome geometry, which involve different numbers of lamps and whose placement is varied according to the requirements of the upcoming application. Several versions deliberately overlap the radiation emitted by two or more lamps (as shown in Figure 9A and Figure 9B ), while other versions do not. The overall assembly of the lamps can be cooled by flowing dry or research-grade nitrogen, He, or other (VUV / UV non-absorbing) gases through the assembly at a slow rate. A slow gas flow rate is desirable to minimize turbulence and refractive index variations within the dome assembly.

[0077] Figures 15A to 18M illustrates a radial lamp arrangement in which flat panel lamps 120 are arranged along an N-sided star pattern (where N is an integer > 3), and the combined radiation of the lamps directed towards the axis of the system is guided by a conical reflector 124 through an annular emission aperture 122. A housing 126 houses the lamp arrangement. As shown in Figure 16B , the reflector is omitted for clarity, and a dielectric 130 isolates a first electrode 132 that supplies energy to the top first electrodes of each lamp 120 from a second electrode that supplies energy to the bottom second electrodes of each lamp 120.

[0078] Referring to Figure 17A and 17B , the interior portion of the housing 126 contains slots or rails 140 for physically positioning the flat lamps 120. In the case of omitting the electrodes of the housing, the lamp contacts 142 that are electrically connected to those electrodes are visible, and the reflective inner surface 144 of the housing is illustrated. In this geometry, the lamps 120 are mounted into a housing 126 that positions the lamps such that they are not parallel to each other but form an angle with respect to each other. This geometry is used to direct the radiation from each lamp onto a conical reflector 124 whose axis coincides with the optical system axis perpendicular to the emission aperture. The conical reflector 124 has a highly reflective surface (at the desired (wavelengths)) on the outer surface of the cone. Additionally, in a manner similar to that with respect to Figures 10A to 10CIn the same manner discussed, a single lamp can be easily removed by removing the housing cover. In other embodiments, the radial array can have angled (i.e., having a "serrated" structure) and reflective inner walls in order to deflect VUV / UV radiation towards the axis of the system, so that the conical reflector then directs the radiation out of the housing and towards the surface to be illuminated. Again, dry nitrogen gas can flow through the lamp housing in order to cool the mirrors and the lamp. It is desirable to process the nitrogen gas in an external closed-loop flow system (which may be cryogenic) in order to remove impurities in the gas stream that can strongly absorb at the (multiple) wavelengths of the lamp.

[0079] Roll-to-roll processing system

[0080] Because for example for lamp intensities above ~50 mW / cm 2 the lamp exposure times required to pattern thin acrylic / PMMA and other organic films with a 172 nm lamp are very short (on the order of a few seconds), it is now possible to use roll-to-roll systems to implement lithography, such as Figures 19A to 19B (double-sided processing) or Figures 19C to 19D (single-sided processing) as shown in the roll-to-roll systems. An organic polymer film 160 having a predetermined thickness can be fed from the roll 160 on the right in FIG. 19. The film passes under a photomask having a desired architecture (pattern, network, etc.) as Figure 1 shown. During its traversal of the system, any portion of the acrylic film must be exposed to the (multiple) VUV / UV radiation sources 164 for a predetermined time. The exposure time will depend on the (multiple) lamp intensities and the composition and thickness of the polymer film, as well as the distance from the radiation source to the surface. Thus, the speed of the film will depend on several factors and can be easily calculated. It is advantageous to expose the polymer film with an array of lamps of extended length so that a larger area of material can be processed simultaneously. This will also allow for an increase in the speed of the film surface. Finally, it should also be mentioned that the organic polymer film can have a paper backing during processing. Different polymer films of commercially available products have a paper backing that will minimize or prevent damage to the film during the transport of the film through the system. After exposing the film to the VUV / UV source and thus patterning it, the paper backing can be easily removed. If the organic polymer does not have a backing, it is also possible to irradiate the film from both sides. In this case, one pattern or device can be formed on one side of the film, and a second pattern, device, or optical component can be produced on the opposite side of the polymer film.

[0081] Two processes carried out in a single chamber

[0082] By simply switching the gas flow with conventional mass flow controllers and valves, Figure 1Embodiments can also be used for two or more processes. For example, for a lamp emitting at 172 nm, lithography can be performed by the processes described above. During this lithography process, chamber 14 can be evacuated, or a dry nitrogen stream can be passed through chamber 14 because this gas has no significant absorption at 172 nm. Thus, this gas will not have any detrimental effect on the lithography process.

[0083] Another embodiment is shown in Figure 20 and is based on Figure 1 a plurality of features of Figure 1 All features of Figure 20 are incorporated into Figure 20 In the system of Figure 20 a UV / VUV lamp or an array of lamps 170 is located in its own chamber 172 adjacent to the processing chamber 174. Window 176 allows VUV / UV radiation to pass between the two chambers. One again has the option of evacuating the upper chamber 172 of the two-chamber system, or flooding (as opposed to static gas filling) this chamber with dry nitrogen which would normally flow. Figure 20 The window 176 at the center of Figure 20 can be made of any material that is effectively transmissive at the (multiple) wavelengths of the lamp(s). For a lamp emitting 172 nm, this material includes fused silica, quartz, sapphire, magnesium fluoride, and other materials. Figure 1 The lower chamber 174 of Figure 20In the lower chamber. After the first mask is mounted on (or in close proximity to) the substrate, the chamber is evacuated and the polymer film is exposed by light passing through the photomask. This process opens "windows" in the polymer film for further processing. A second process may involve the same mask or a switch to a second mask, after which the flow of the first gas mixture is initiated. If the next step is to etch the exposed area of the substrate, a mixture composed of CCl4 vapor and a noble gas such as Ar (for example) is introduced into the chamber through a mass flow controller. Commercial plasma tools typically use carbon tetrachloride to etch semiconductor wafers such as silicon. However, as a result of, for example, CCl4 molecules absorbing 172 nm photons, the C-Cl chemical bond breaks, releasing both chlorine atoms and carbon atoms. Thus, both lithography and etching can be performed in the same chamber using a semiconductor wafer or other substrate with the same lamp or lamp array in place.

[0084] Similar comments can be made regarding the process of film deposition. It is well known that metal-containing precursor molecules (such as trimethylaluminum (TMA) or triethylgallium (TEG)) are photo-dissociated by 172 nm photons. That is, for example, the Al-CH3 bond in TMA is broken by the absorption of one or more photons, ultimately releasing Al atoms. Thus, films of virtually any metal (Al, Ag, Au, Cu, etc.) can be deposited into the windows in the photomask by the photo-dissociation of an appropriate precursor (CuAcAc for Cu, TMA or TEA for Al, etc.). Similarly, compound semiconductor materials such as AlN or GaN can be grown by irradiating a mixture composed of TMA and ammonia (NH3) with a lamp or lamp array. Both molecules are known to have strong absorption at 172 nm. In the past, films such as AlN or GaN were typically grown by thermal processes such as MOCVD or MBE, but the availability of efficient lamps operating in the UV / VUV region has opened the door to (non-thermally) breaking the bonds of a wider array of molecules than previously possible. Thus, the same lamp can be used for the processes of lithography, etching, and deposition. Since the nature of the processes occurring in the Figure 1 and Figure 20 chamber depends mainly on the properties of the gas, multiple gases, or vapors introduced into the chamber through computer-controlled valves and mass flow controllers, the system is capable of quickly switching from one of these three processes to another. An exemplary application is the growth of superlattices comprising alternating layers of GaN and AlN (such as an AlN / GaN heterostructure).

[0085] Two or more lamps of different wavelengths

[0086] Engineering of process sequences can require two or more lamps of different wavelengths. Since lamps with wavelengths of 126 nm, 147 nm, 222 nm, 308 nm, and other wavelengths are now available in a flat form factor, it is possible to irradiate a mixture consisting of a gas or vapor with a specific lamp emitting a first wavelength, which interacts only with one of the gases in the mixture. For example, a lamp with a wavelength of 222 nm (emitted by KrCl molecules) has photon energy capable of photodissociating several alkyl metals but not ammonia (see "Photochemical Vapor Deposition", 1992). However, the 172 nm wavelength of the Xe2 lamp can dissociate both molecules. Thus, those skilled in the art will recognize combinations of gases / vapors and lamps that enable rapid film deposition or etching.

[0087] When two lamps of different wavelengths are required, Figure 21 and Figure 22 illustrates two embodiments that are Figure 1 or Figure 20 modifications of either and allow incorporation of at least two lamps into the system. In Figure 21 , a first lamp 182 emits at a first wavelength transmitted by a beam splitter 184, and a second lamp 186 has a second wavelength reflected by the beam splitter 184. As shown in Figure 21 , the different wavelengths are directed through a window 188 and a mask into a processing chamber leading to a substrate 190. Alternatively, as shown in Figure 1 , the beam splitter and lamps can be located inside the chamber. Figure 22 shows an in-chamber arrangement based on Figure 1 that includes two first lamps 182 and two second lamps 186 arranged such that a beam splitter is not required. As in Figure 21 , additional details are disclosed in Figure 1 and Figure 20 .

[0088] Small-scale lithography systems

[0089] Figure 23A and 23B are diagrams of small-scale lithography systems that are inexpensive and suitable for educational and small industrial applications that do not require the highest available spatial resolution (feature size). The diagram in the upper part of FIG. 23 is a complete small-scale system designed for lithography with a 10 cm × 10 cm (4" × 4") VUV / UV lamp. Initial tests have been carried out using a 172 nm lamp, but depending on the application, other wavelengths (such as 147 nm and 222 nm) are also acceptable. We believe that compared with Figure 23A and 23BThe consistent experimental system is considered to be one of the smallest lithography systems, perhaps the smallest ever. The system is sized to fit on a small table or laboratory bench and can be held in the hand with a width and depth comparable to a typical paperback book and a height comparable to a coffee cup. The current dimensions of the experimental system are: width: depth: height = 105 mm x 190 mm x 115 mm.

[0090] Figure 23A Details of the disassembled assembly are shown, and Figure 23B is also a view of the assembly, but with the sample flood exposure drawer holder 200 shown open. Flood exposure (without a mask) is useful for cleaning the sample surface and making it hydrophilic. The sample flood exposure drawer holder slides (or is mounted on rollers or bearings) into the flood exposure body 202, which defines a flood processing chamber therein and contains a purge gas fitting 204 that allows a purge gas such as nitrogen or a noble gas to enter or be evacuated from the chamber. A window 206 covers most of the body 208 that defines the lamp / mask / substrate chamber. The body 208 is preferably constructed of an ultraviolet light-blocking polymer, which can also be used as the material for other components of the assembly. The flood exposure body 202 and the body 208 contain seals (not shown) for sealing the window 206 and all other components connected to or in contact with these bodies. The first body cap 210 provides a gas fitting for the lamp chamber, while the opposite second body cap 212 also provides a gas fitting and supports a flat UV / VUV lamp 214 within the chamber and emits radiation in two directions (toward the flood exposure drawer 200 and in the opposite direction upward toward the mask 222). A pair of electrodes 216 extends from the second body cap 212, and the electrodes are configured to be firmly mounted and in electrical contact with the respective first and second lamp electrodes of the lamp 214. The electrode cap 218 provides electrical contact from an external power source to the pair of electrodes 216. The mask holder body 220 defines a recess for mounting the mask 222, contains holes / openings through which VUV / UV radiation passes, and seals the window 224 to the top of the body 208. The latter also has top and bottom openings / holes. The sample holder 226 is spring-loaded onto the mask holder cap 228 that contains a purge valve. The sample is placed face down on the mask. The sample holder 226 can apply pressure to form a good contact between the mask and the sample. When the sample is installed and the chamber contains the appropriate gas, mixture, or vacuum, the system operates as described for the Figure 20 system shown schematically. If the sample is a bulk polymer, no layers are required. If the sample is a semiconductor wafer, a polymer coating is applied before exposure to the lamp.

[0091] In Figure 24Additional features are implemented to speed up the introduction and exposure of new samples (substrates) to the system. Specifically, it is not necessary (for example) to place the substrate into a vacuum-sealed chamber (as shown in Figure 20 or Figure 23A and Figure 23B ). Figure 24 Labeled with the same reference numerals as Figure 20 . As shown in Figure 24 , positioning the photomask / substrate combination near the bottom surface of the chamber without vacuum contact with the bottom surface of the chamber is equally satisfactory in many applications. If N2 flows into the processing chamber 174, it will escape into the chamber air through a small gap 230 (< several mm) between the wall of the processing chamber 174 and the substrate or substrate holder. Such a system can significantly speed up the lithography process because there is no need to evacuate the chamber air initially located in the lower chamber of Figure 20 and Figure 24 . "Spraying" the photomask 178 and the wafer 180 with dry N2 is inexpensive, does not require a vacuum pump station, and it is safe to exhaust nitrogen into the chamber air.

[0092] Polymer microsphere photoablation

[0093] In particular, the ability of 172 nm photons to ablate polymers opens the door to a number of valuable processes in photonics and optoelectronics. For example, Figure 25 is an optical micrograph of an array of closely packed polyimide spheres located on a substrate. When the array is irradiated with 172 nm flat lamps, the diameter of the microspheres is uniformly reduced by photoablation. Figure 26 Shows a portion of the same array after illumination with a 172 nm lamp Figure 25 . The microspheres no longer touch but now form a two-dimensional array, which is valuable for microsphere or nanosphere lithography or optical components containing gratings.

[0094] Figure 27 is a diagram of a preferred system designed for irradiating two-dimensional (2D) microsphere crystals, which uses Figure 1 and Figure 20features, but includes mounting options specifically designed for these 2D crystals. The system includes a frame 240 with multiple slot positions 242 that can hold a substrate holder 244 at different distances from a UV / VUV lamp 246. The lamp 246 is mounted in a recess of a lamp holder 248 that defines a hole, and the first and second electrodes of the lamp can be accessed from above. The substrate holder 244 includes a recess for mounting a substrate 250 with an ordered array of nanospheres or microspheres at any position provided by the slots 242. With this simple design, VUV and UV lithography systems have been demonstrated, and the system employs "rarefaction" of polymer microspheres in a large array in order to obtain optical components and systems such as gratings. In combination with a photomask, Figure 27 the system can achieve optical networks, lenses, arrays of microspheres, and a wide variety of other optical components. As an example, Figure 26 the microsphere 2D grating has a reflection spectrum that can be changed ("tuned") by continuing to illuminate the array with 172 nm radiation. That is, the effect of the 172 nm radiation is to decrease the diameter of the microspheres or nanospheres while increasing the sphere-to-sphere distance (pitch). Both particularly affect the reflectivity's dependence on wavelength and the wavelength of maximum reflectivity. Thus, with an appropriate duration of 172 nm lamp radiation, lamp intensity, and initial sphere diameter, a desired reflection spectrum can be obtained.

[0095] Regarding the wavelength of the lamp, a separate comment is in order. At the time of this application, flat lamps that radiate at 147 nm, 172 nm, 222 nm, 240 - 260 nm, and 308 nm are commercially available. Additional wavelengths are expected to appear on the market in the coming years. Although 172 nm, for example, appears frequently in this document, it is quite possible that lamps emitting at other nearby wavelengths (e.g., 165 - 200 nm) will be equally effective or more effective for the processes and devices mentioned here, since such lamps are expected to be able to directly ablate polymer layers. Thus, particular attention is currently paid to 172 nm, 180 - 200 nm, and 222 nm, but other wavelength ranges (such as 160 - 170 nm and 180 - 200 nm (under development)) are specifically incorporated into any patent application.

[0096] Hydrophilic polymer surface

[0097] Experiments have shown that VUV radiation of a wide range of organic polymers in the shortest time periods renders the surfaces hydrophilic. Typically, such polymer surfaces are hydrophobic, which is the term indicating that water "beads up" on the surface. Thus, glasses constructed of one of several polymers, for example, will typically quickly "fog up" in humid and marine environments. However, it has been found that most organic polymer surfaces become hydrophilic when irradiated with VUV at 100 mW / cm 2Radiate for 15 seconds at the intensity of , converting the surface from hydrophobic to hydrophilic. A series of extensive tests have demonstrated that after VUV radiation, the contact angle of water droplets on the polymer surface drops sharply. A large contact angle indicates a hydrophobic surface, while a small contact angle demonstrates a hydrophilic surface.

[0098] For the fields of optics and fluidics, the significance of the hydrophobic-to-hydrophilic transition of the polymer surface accompanied by VUV radiation of the surface is substantial. As an example, Figure 28A and Figure 28B are photographs of an optical imaging system that includes a polymer film or sheet. In the left photograph, the polymer plate is shown oriented at an angle such that the steam from hot water (in the cup at the bottom of the photograph) will strike the polymer surface. In Figure 28A the outer face of the polymer plate has been radiated by a 172 nm lamp at an intensity of 15 mW / cm 2 for 60 seconds. In this instance, the polymer surface is hydrophilic, and the steam reaching the surface is dispersed into a thin film of uniform thickness. Thus, although the polymer surface has been exposed to steam for a long time, the performance of the optical system is not affected, and the image in the upper right corner can be observed.

[0099] Figure 28B shows the same imaging system and test setup, except that the polymer plate has not been radiated by the VUV lamp. In this case, the steam reaching the polymer plate forms numerous micro-droplets (array), which severely scatter the incident visible light. Thus, the imaging system can now not detect the image, as shown at the lower right corner of Figure 28B .

[0100] A large number of tests confirm Figure 28A and Figure 28BAs a result, it is now possible to fabricate spectacles, goggles, and other eye-wear that do not "fog" in humid or marine environments. Such eye-wear can consist of lenses made of suitable polymers, or they can be made of glass or other optical materials and simply coated with a thin polymer film. Additionally, camera lenses can also be coated with a polymer film treated with VUV radiation to render them fog-resistant. This simple change in the design of optical components such as windows and lenses is expected to result in a substantial improvement in the performance of optical systems in marine environments or unusually humid locations. Similarly, the windshields of automobiles and trucks can be coated with a thin layer of polymer that will be hydrophilic when treated with VUV radiation, and thus can prevent water from beading. This treatment is expected to greatly improve the visibility of motorists in rainy conditions. This hydrophobic-to-hydrophilic transition is also expected to improve the flow of water through channels, especially microchannels. Because hydrophilic surfaces form a thin layer of water at the surface, the turbulence of the water flow in contact with this surface layer is expected to be less than that typically present when water flows over a hydrophobic surface. Thus, the polymer microchannels in biomedical devices such as microfluidic arrays can be irradiated with a VUV lamp for at least 30 seconds and have their flow characteristics altered. Moreover, the VUV-induced hydrophobic-to-hydrophilic transition of polymer surfaces can be achieved on a roll-to-roll basis as described above.

[0101] In a similar manner as described above, for example, it is expected to produce hydrophilic surfaces on metals and glass fibers to reduce drag on the underwater surfaces of moving objects or the hulls of marine vehicles.

[0102] Although specific embodiments of the invention have been shown and described, it should be understood that other modifications, substitutions, and alternatives will be apparent to those of ordinary skill in the art. Such modifications, substitutions, and alternatives can be made without departing from the spirit and scope of the invention, which shall be determined by the appended claims.

[0103] The various features of the invention are set forth in the appended claims.

Claims

1. A photolithography method without a photoresist, the method comprising: Providing an organic polymer; Providing at least one mask with a desired pattern to be created in the organic polymer; Placing the organic polymer in a chamber; Creating a vacuum or an inert atmosphere in the chamber; Generating photons with a micro-plasma flat lamp photon source; And Directing the photons through the mask to perform non-thermal ablation to create the desired pattern in the organic polymer or to photochemically alter portions of the organic polymer for removal by a solvent, and then removing the portions to form the desired pattern in the organic polymer.

2. The method according to claim 1, wherein, The organic polymer includes a polymer sample to be patterned.

3. The method according to claim 1, wherein The organic polymer includes a layer on a material substrate.

4. The method according to claim 3, wherein The organic polymer includes polymethyl methacrylate, CR 39, ABS, or PET.

5. The method according to claim 1, wherein, The micro-plasma flat lamp photon source includes a lamp that generates photons at 172 nm or within a wavelength range of 160 - 170 nm or 180 - 200 nm.

6. The method according to claim 1, wherein in the case of a vacuum or an inert atmosphere, the non-thermal ablation and the removal of the portions are performed in a single chamber.

7. The method according to claim 1, wherein The organic polymer includes a layer on a material substrate, and the method further includes: Introducing a deposited molecular precursor into the chamber containing the material substrate, on which a patterned thin film is present; and Breaking the bonds in the precursor with photons from the micro-plasma flat lamp photon source, thereby depositing the product of the precursor on the material substrate in the desired pattern.

8. The method according to claim 7, wherein under vacuum, the non-thermal ablation, the removal of the portions, the introduction of the deposited molecular precursor, and the deposition of the product are performed in a single chamber.

9. The method according to claim 7, wherein, The layer includes polymethyl methacrylate, CR 39, ABS, or PET.

10. The method according to claim 1, wherein The micro-plasma flat lamp photon source includes a lamp that generates 172 nm photons and a second micro-plasma flat lamp photon source with a different wavelength, the second micro-plasma flat lamp photon source emitting mainly at 147 nm, 160 - 170 nm, 172 nm, 180 - 200 nm, 222 nm, 240 - 260 nm, and / or 308 nm.

11. The method according to claim 1, wherein The organic polymer includes a layer on a material substrate, and the method is not performed in a vacuum chamber, but rather allows a continuous gas flow of an inert gas into the chamber and over a mask near the surface of the material substrate.

12. The method according to claim 1, wherein, The organic polymer includes a layer on a material substrate, and the method further includes an additional step of etching the layer and / or the material substrate: the additional step uses the mask, or switches to a second mask, and provides a gas or a gas mixture to etch the material substrate.

13. The method according to claim 1, further comprising transferring the pattern formed in the organic polymer to another material.

14. The method according to claim 13, wherein, The another material includes metal or ceramic.

15. The method according to claim 1, wherein, The organic polymer includes a roll-to-roll material that is moved past the mask.

16. The method according to claim 1 further comprises changing the orientation of the at least one mask or providing a second mask and then repeating the generation and directing to add complexity to the pattern.

17. The method according to claim 1 further comprises loading the organic polymer into an electron beam lithography tool and adding smaller features to the pattern via electron beam lithography.

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