By the electron beam lithography (EBL) process combined with the self-aligned double patterning (SADP) process, SiN hard masks (HMs) were successfully fabricated on a 300 mm wafer for a variety of gate lengths around 2x nm. The SiN is deposited by low-pressure chemical vapor deposition (LP-CVD) in the fine trenches with a bottom width of 18 nm in the tetraethyl orthosilicate (TEOS) layer etched by the EB resist mask drawn. After the selective SiN CMP on TEOS followed by selective TEOS etching, a 25 nm wide and 57 nm high SiN HM was successfully fabricated on a Si wafer, which will be replaced by an amorphous Si film for dummy gates. Consequently, we have confirmed that an 18 nm wide and 71 nm high Si structure was fabricated by the subsequent etching using the SiN HM. Electron beam lithography using a tone reversal process (EB-R) is valid and useful especially for R&D stages of LSI devices due to the flexible pattern size design.

Plasmonic color is a structural color generated via preferential light absorption and scattering in dielectric nanostructures. In this study, a large plasmonic color image was successfully fabricated by an electron beam lithography (EBL) system. A software program, referred to as P-color in this study, was developed to facilitate the conversion of a desired color bitmap image to a GDS file composed of multiple nano-patterns to realize plasmonic color. The relationship between the color, width, and pitch of the pattern structures was investigated under different area-dose conditions during EBL as basic data for plasmonic color image design. After establishing conversion techniques for both the large-capacity GDS and EBL files, a plasmonic color image sample with a size of 60 mm x 40 mm area (which is difficult to fabricate using a conventional point-type EBL system) was successfully fabricated.

Nanoimprint lithography (NIL) is promising for the processing of dual damascene structures fabricated in back-end-of-line layers, and initial development began with a simple single-level process to evaluate NIL's suitability. In this work, a test element group (TEG) pattern with a 70 nm half-pitch was selected, and copper (Cu) filling and chemical-mechanical polishing were performed after NIL pattern transfer. The results were compared with those obtained from the same TEG layout and processes but using ArF immersion lithography instead of NIL. Those obtained by NIL showed high pattern fidelity for all the designed layouts, whereas the resist patterns varied from the designed shape for ArF immersion lithography. The line resistances of Cu interconnects patterned by NIL showed good cumulative distributions at line widths ranging from 60 nm to 78 nm in 2 nm increments, without line breaks or space narrowing of SiO2. NIL showed potential for interconnect patterning with high-precision line width control.

Electron Beam Lithography (EBL) has a capability to fabricate fine patterns with nanometer order, and is thought to be one of the possible technologies to fabricate a nanoimprint mold with the pattern size less than several 100 nm. We have developed Ultra-High Throughput EBL system, which equipped an Electron Optical Column (EOC) with a large beam current, and a large deflection field for fabricating a nanoimprint mold with wafer size. “ELF-10000” is the first model of our Ultra-High Throughput EBL, which has a deflection field of 10 mm square. And, we achieved to the drawing time of 4 hour 14 minutes to fabricate a mixed pattern of micron size and nanometer sizes on entire surface of 8 inch wafer. Moreover, we have improved the field stitching accuracy of the EBL system, and released the new model “ELSHAYATE”. It has 5 mm square field size, which is a half of the first model and has the field distortion less than half. This new model is expected to be a useful tool for nanometer order pattern drawings on the area larger than 10 mm square, which may have several possible applications for wafer size nanoimprint mold.

Droplet-dispensed ultraviolet nanoimprint lithography (UV-NIL) in helium enables adaptive material deposition to match pattern variations in a mold. It is a potential lithographic technology for semiconductor devices, but process throughput is an issue. UVNIL in trans-1,3,3,3-tetrafluoro-propene (TFP) and 1-chloro-3,3,3-trifluoropropene (CTFP) gases has enabled bubble-free and high-throughput processes for spin-coated films. This study investigated the applicability of a mixed condensable TFP/CTFP gas to dropletdispensed UV-NIL. The filling time in a local area of the mold in a mixed condensable gas atmosphere was as low as 1/30th that in helium. Similarly, the filling in the entire mold was faster in a mixed condensable gas atmosphere than in helium, and micropatterns could be filled within 1.6 s. When the droplets were exposed to the mixed TFP/CTFP gas, the droplet diameter of 108 mu m increased to 127 mu m owing to gas absorption. The quality obtained for an L/S 90-nm pattern was the same as for the pattern of a spin-coated film, but the line width of patterns fabricated by UV-NIL in ambient TFP/CTFP was 6 nm narrower than that for UVNIL in He.

Bubble-free filling is required to realize high-throughput mass production in ultraviolet nanoimprint lithography (UV-NIL). UV-NIL in 1-chloro-3,3,3-trifluoropropene (CTFP) and trans-1,3,3,3-tetrafluoro-propene (TFP) gases has enabled bubble-free UV nanoimprinting of spin-coated films without a vacuum. We evaluate the amount of gas dissolution of 24 organic solvents, which was measured using an electronic balance in a glove box with saturated gases of CTFP and TFP, and use the Hansen solubility parameters (HSP) for analysis. Although the HSP teas graph indicated the same solubility trend in TFP and CTFP atmospheres, the amount of TFP gas dissolution was 1/5th that of CTFP. The pattern quality of acrylate UV-curable resins, which absorb well the condensable gases, was also demonstrated by altering the fraction of the introduced condensable gas mixture of TFP/CTFP. Fine line patterns with a width of 16 nm were obtained by UV-NIL with a high TFP fraction (>66%) in the TFP/CTFP mixed gas atmosphere.

High-aspect-ratio microstructures (HARMS) of polyimides have many applications, such as components of microelectromechanical systems and X-ray gratings. This study demonstrates the fabrication of HARMS with vertical and smooth sidewalls in a thick, soluble block-copolymer polyimide (SBCP) film by an UV-assisted thermal imprint process. A preheating condition was controlled as a parameter that dominated the imprint pattern fidelity. After investigating a proper prebaking condition, patterns with a width of 3.4 μm and a height of 35.1 μm with a high-aspect ratio of 10 were successfully structured in an SBCP film that has a thickness of approximately a hundred micrometers. The process has potential as a low-cost fine pattern fabrication process for polyimide-based polymers.

A software program for modifying a mold design to obtain a uniform residual layer thickness (RLT) distribution has been developed and its validity was verified by UV-nanoimprint lithography (UV-NIL) simulation. First, the effects of granularity (G) on both residual layer uniformity and filling characteristics were characterized. For a constant complementary pattern depth and a granularity that was sufficiently larger than the minimum pattern width, filling time decreased with the decrease in granularity. For a pattern design with a wide density range and an irregular distribution, the choice of a small granularity was not always a good strategy since the etching depth required for a complementary pattern occasionally exceptionally increased with the decrease in granularity. On basis of the results obtained, the automated method was applied to a chip-scale pattern modification. Simulation results showed a marked improvement in residual layer thickness uniformity for a capacity-equalized (CE) mold. For the given conditions, the standard deviation of RLT decreased in the range from 1/3 to 1/5 in accordance with pattern designs. (C) 2018 The Japan Society of Applied Physics

Ultraviolet nanoimprint lithography (UV-NIL) is a recently developed technology that allows low-cost nanofabrication. Bubble-free filling needs to be achieved to realize high-throughput mass production in UV-NIL. Although bubble-free filling can be accomplished by performing UV-NIL under vacuum, nonvacuum processes can lower equipment and operation costs. Polydimethylsiloxane (PDMS) is known as a gas transmittable materials due to its molecular feature and used for flexible molds in UV-NIL. In this work, we investigated the effects of UV-NIL using PDMS mold for filling behaviors and mold release force in different atmosphere. Bubble-free filling of UV-NIL was successfully demonstrated in air, and 1, 1, 1, 3, 3-pentafluoropropane (PFP) gas atmosphere. The average release force following UV-NIL in PFP was 8.14 N, which is 52 % smaller than that following UV-NIL in air. Fine nanopatterns with 250 nm width were successfully fabricated by UV-NIL in PFP atmosphere without any defects.

It is important to systemize mold design methods to enable expansion of nanoimprint lithography (NIL). In NIL, it is necessary to deposit the residual film thinly and uniformly over the entire imprint region, even for non-uniform pattern densities. We propose that this can be achieved by using a capacity-equalized (CE) mold, in which deeper complementary cavities are added to the original trench pattern areas to achieve a uniform pattern capacity per unit area throughout an entire mold with varying pattern densities. In this study, an algorithm for the automated design of a CE mold for NIL was developed to broaden the industrial use of CE molds. The algorithm was used to develop a prototype of a complementary pattern generator. The validity of the method was verified by ultraviolet-NIL simulation. The standard deviation of the residual layer thickness was reduced from 4.75 to 1.55 nm for a mold pattern with density variations from 0.29 to 0.68 by modifying the mold design.

UV nanoimprint lithography (UV-NIL) in condensable gases such as pentafluoropropane (PFP) has been recognized as one of the most promising methods to realize bubble-defect-free UV-NIL with low demolding forces when compared with that in ambient air and He. We have recently studied two condensable gases [trans-1-chloro3,3,3-trifluoropropene (CTFP) and trans-1,3,3,3-tetrafluoropropene (TFP)] with different vapor pressures and low global warming potentials (GWP) of <6. However, the resulting lithographic pattern quality in UV-NIL remains unclear using CTFP and TFP. In this work, the surface roughness of patterns fabricated using UV-NIL in the CTFP and TFP gases was investigated. In UV-NIL in a CTFP/TFP atmosphere, with an increase in the TFP fraction, the surface roughness decreased. It was also found that the linewidth of tens of nanometer size patterns can be linearly controlled by adjusting the CTFP/TFP fraction; for 70-nm-wide line patterns, the linewidth adjusting ratio was approximately 14%.

Ultraviolet nanoimprint lithography (UV-NIL) in pentafluoropropane (PFP) is recognized as one of the most promising methods to achieve ultrahigh-speed UV-NIL without air bubble defects. Although liquefied PFP dissolved in the resin reduces the resin viscosity and demolding force, it also causes large shrinkage of the pattern and degrades the pattern quality compared with that achieved in air or He environments. In this work, UV-NIL in trans-1,3,3,3-tetrafluoropropene (TFP), which has a higher vapor pressure than that of PFP, was investigated with respect to throughput and pattern quality characteristics to find an alternative to PFP. Bubble-free filling of UV-NIL was demonstrated in an TFP atmosphere: the cavity-filling time was about four times shorter than that in He, and the fine values of line edge roughnesses comparable to those achieved in air or He were obtained.

Bubble-free filling needs to be achieved to realize high-throughput mass production in ultraviolet nanoimprint lithography (UV-NIL). Although bubble-free filling can be accomplished by performing UV-NIL under vacuum, nonvacuum processes can lower equipment and operation costs. UV-NIL in 1,1,1,3,3-pentafluoropropane (PFP) has been recognized as a promising method of realizing ultrahigh-speed UV-NIL; however, the global warming potential (GWP) of PFP of 1030 might restrict its industrial use. In this work, UV-NIL of a spin-coated UV-curable resin in trans -1-chloro-3,3,3-trifluoropropene (CTFP), which has a low GWP of <5, was studied with the aim of identifying an alternative to PFP. The cavity filling speed of resin and mold release force in CTFP were comparable to those in PFP, and superior to those in helium atmosphere. Sub-100 nm patterns were successfully fabricated by UV-NIL in CTFP, although the line width shrinkage ratio of patterns fabricated in CTFP was slightly larger than that of patterns fabricated in PFP.

Using a full-area monitoring system based on dark-field illumination, we investigated the use of resin filling of UV nanoimprints to fabricate large checker patterns with edge lengths up to 400 lam at thin resin layers (<100 nm). We confirmed that filling mainly proceeds because of the capillary pressure of the resin between the mold and wafer. While analyzing the filling process, we derived a modified Stefan's formula that accounted for this capillary pressure. Comparing with measured data we found that the modified formula predicted filling times better than the traditional formula, but filling occurred more rapidly than the predictions for thinner resin layers. (C) 2015 Elsevier B.V. All rights reserved.

It has been difficult to fabricate high-resolution patterns in polyimide film because a polyimide is difficult to dissolve out or to etch. In this paper, polyimide-based polymer patterning with several hundred nanometers took on the challenge of nanoimprinting on soluble block copolymer polyimide (SBC-PI) at a relatively low temperature of 130 °C. The high-resolution patterns with 118 nm in width and high-aspect-ratio patterns of 6.5 were successfully fabricated without any defects. After hard-baking at 200 °C to enhance the thermal stability, the pattern deformation ratios for height and width were less than approximately 10% for the patterns in a width of 100 nm.

Needs for an inexpensive and simple technology for fabricating fine copper (Cu) patterns on a polyimide (PI) film have been increasing. In this study, vacuum-UV induced surfactant masking (VISM) process was proposed as a tool for simplifying selective electroless Cu plating. The electroless Cu plating process using VISM is capable of Cu patterning on solvent-soluble siloxane-modified polyimide (PI) without photoresist patterning steps unlike conventional electroless Cu plating process. The relation between the wettability of SBC-PI film surface and the UV/Ozone treatment time was investigated to establish VISM process condition. The feasibility of the proposed process was verified by demonstrating the fabrication of Cu/PI patterns with widths ranging from 5 mu m to 50 mu m and measuring an electric property of some patterns.