Materials For Lithography Research Articles

Surface energy tailoring of glass by contact printed PDMS

A simple contact printing method to modulate the surface wettability of glass employing poly(dimethyl)siloxane (PDMS) mold was investigated. PDMS is a well known material in microfluidics and soft lithography for biomedical applications, being easy to process, low cost, biocompatible and transparent. Moreover its wettability can be tuned, by the exposure to oxygen plasma, UV-ozone or chemical oxidant solutions, or by surface functionalization. Unfortunately the effects of these treatments are not so stable in time. In this work a method to modify the surface energy (SE) of PDMS by changing its composition is proposed. Different mixing ratios (polymer base/curing agent) are analyzed evidencing that SE decreases while increasing the content of the polymer base, permanently modifying the surface behavior. As a thin layer of PDMS can be transferred to glass surfaces by contact printing, it is possible to locally change the wettability of glass simply patterning PDMS. In this work a SE patterning technique for glass surfaces by PDMS transfer is proposed. The technological process is based on the fabrication of PDMS molds by lift-off technique using Laser Direct Writing (LDW) lithography to process commercial photoresist. The transferring process for structures having a width of 10μm was studied for a chosen PDMS composition, analyzing the surface energy of the patterned thin film by contact angle (CA) measurements.

Fabrication of Diamond Nanopit arrays by Room-temperature Curing Nanoimprint Lithography Using Glass-like Carbon Molds

ABSTRACTWe have proposed the use of glass-like carbon (GC), as mold material because the 27-maximum etching selectivity of polysiloxane film against GC, which was approximately sixtimes larger than that of polysiloxane film against chemical vapor deposited (CVD) diamond film. We have investigated the fabrication of diamond nanopit arrays by room-temperature curing nanoimprint lithography (RTC-NIL) using GC mold, as applications to the emitter and the micro-gear. The polysiloxane has in the state of sticky liquid at room-temperature and negative-exposure characteristic. Therefore, the polysiloxane was used as RTC-imprint resist material, and also used as electron beam (EB) resist (oxide mask) material in EB lithography. We have fabricated the cylindrical GC nanodot mold with 500 nm-diameter, 600 nm-height and 2 μm-pitch. We carried out RTC-NIL using GC mold under the following optimum conditions: time from spin-coating to imprint of 1 min, imprinting pressure of 0.5 MPa and imprinting time of 5min. Then, we have processed the diamond film with an electron cyclotron resonance (ECR) oxygen ion shower. We have fabricated diamond nanopit array with 250 nm-depth and 500 nm-diameter. The diameter of diamond nanopit pattern was in good agreement with that of GC mold. Moreover, the depth of the diamond nanopit patterns fabricated by RTC-NIL using cylindrical GC mold was three times larger than that using conical diamond mold.

UV nanoimprint lithography of 70 nm half pitch line pattern using plant-based resist material with lactulose derivative derived from biomass and medicinal drugs

Plant-based resist materials have great potential for environmentally compatible bio-nanofabrication and have recently been applied as UV crosslinkable materials for nanoimprint lithography. This Letter reports an UV nanoimprint lithography using plant-based resist materials with lactulose derivative derived from biomass and medicinal drugs. Seventy nanometres half pitch line patterning was demonstrated in the specified UV nanoimprint conditions of etching multilayer processes using silicon-based middle layer and novolac-based bottom layer. Lower film thickness shrinkage of the newly developed lactulose derivative resist material than that of acrylate-based resist material was one of the keys to achieving high-resolution nanoimprint patterns.

Application of Polymers to Photoresist Materials

Demands for high performance chips have been drastically increased along with the development of smart phones, tablet-PCs and so on. Scaling is an ongoing challenge to fabricate a chip with multi-functions in a limited space for semiconductor manufacturers. In accordance with the design rules, critical dimensions (CD) have shrunk in half every two years. Scaling has been realized by making a photolithography pattern finer and finer by implementing a light source that has a shorter wavelength for lithography. In the development of photoresists for each wavelength, such as g-line, i-line, KrF and ArF, it is necessary to select suitable polymer platforms in order to obtain transmittance of the wavelength being used. This report introduces the history of the development of photoresist material and describes future lithography materials such as nano-imprint lithography (NIL) and direct self-assembly (DSA) technology.

Three‐dimensional Directed Assembly of Block Copolymers together with Two‐dimensional Square and Rectangular Nanolithography

Self-assembling sphere-forming block copolymers that normally adopt a hexagonal packing in thin films are directed to assemble on chemically patterned surfaces into their three-dimensional bulk-like body-centered cubic morphology; two-dimensional manufacturing-relevant patterns with square and rectangular symmetry can be derived from the films using molecular transfer printing at a resolution beyond the limits of current lithographic tools and materials.

D4H/D4V Silicone: A Replica Material with Several Advantages for Nanoimprint Lithography and Capillary Force Lithography

Reported are demonstrations that D(4)(H)/D(4)(V) silicone (the product of the platinum-catalyzed hydrosilylation reaction between tetramethylcyclotetrasiloxane and tetramethyltetravinylcyclotetrasiloxane) is useful and practical as a replica material for both nanoimprint lithography (NIL) and capillary force lithography (CFL). The multiple advantageous properties of this extremely cross-linked material include UV transparency (for photo NIL and photo CFL), thermal stability (for high printing temperatures), high modulus (for high printing pressures), low surface energy (for easy demolding), and low viscosity precursors (for replicating small scale features). The replication performance of this material was tested using Blu-ray discs with sub-25 nm features and anodized aluminum foil with sub-10 nm features. Structures of ∼5 nm length scale on the surface of the anodized Al were replicated using D(4)(H)/D(4)(V) silicone as a mold material for CFL with a photocurable epoxy resin and for NIL with poly(methyl methacrylate) (PMMA). Features (holes in the anodized aluminum) with aspect ratios of greater than 9 were replicated.

Highly accurate and sensitive surface plasmon resonance sensor based on channel photonic crystal waveguides

A highly sensitive surface plasmon resonance (SPR) sensor based on channel photonic crystal waveguide (PCW) is proposed. The PCW is based on widely used lithographic and nano-fabrication compatible materials like TiO 2 and SiO 2. Gold has been used as a SPR active metal. By rigorously optimizing the different waveguide parameters, we have shown that there is significant transfer of modal power around phase-matching or resonance wavelength which has been utilized to design a compact and highly sensitive sensor for lab on chip. The ultra narrow width (∼765 pm for an interaction length of 10 mm) of surface plasmon resonance curve and sensitivity as high as 7500 nm-RIU −1 will open a new window for bio-chemical sensing applications.

Advancing Technology Through Measurement Science in the NIST Polymers Division

Established in 1962, the Polymers Division in the Material Measurement Laboratory of the National Institute of Standards and Technology (NIST) will soon celebrate its 50 th year as a world leader in polymers research. The mis-sion of the NIST Polymers Division is to serve as the Nation's reference laboratory responsible for producing the measurement methods, standards, and data needed to advance the manufacture and use of “soft” materials (poly-mers and complex fl uids), with the goal of improving industrial competitive-ness and addressing national needs. The NIST mission is unique because the work of the organization focuses on a facilitation role for technology development in the United States through a combination of strict objectivity and the highest levels of technical expertise. In order to maintain the broadest impact in facilitating technical competiveness, the Polymers Division advances the measurement science of polymers and complex fluids rather than engage in the development of new advanced materials for commercial use. NIST focuses on the underlying measurements needed for all companies competing in a particular sector, i.e., the important pre-competitive technical work that is needed to advance the fi eld rather than one company in particular. We develop measurement methods for physical/chemical properties and structure; processing, flow, and transport; and functional properties and performance (electrical, optical, biolog-ical, mechanical) of polymers and complex fluids. Measurement development has often accompanied fundamental break-throughs in polymer science within the Division. Novel measurements have lead to theoretical advances; precision measurements of semicrystalline polymers, polymer blends, and piezoelectric polymers resulted in leading theories of polymer morphology and crystallization kinetics, phase separation kinetics, and the current model for piezoelectric polymers, respectively. Alternatively, theoretical developments have often resulted in breakthroughs in polymer measurements and standards, such as the BKZ theory of non-linear viscoelasticity resulting in improved measurements of mechanical properties and theories for polymer chains in solution resulting in methods and standards for molecular mass distribution. Currently, the Polymers Division consists of nearly one hundred scientists with a broad portfolio of research that includes advanced imaging measurements of the interaction of biological systems with polymer materials, smallangle neutron and X-ray scattering measurements of nanostructured materials, the separation and purifi cation of single-wall carbon nanotubes, and the development of new tests for the reliability of soft body armor. The Division works closely with industry, government, and university partners to ensure that the critical measurement needs of the Nation are being met. For example, the Division has worked with International SEMATECH and Intel on identifying the potential limits of next-generation photoresist materials; the National Institutes of Health on standards development for dental materials; and with university groups around the world including Seoul National University, Stanford University, the University of Delaware, and the University of Colorado. Recent progress in some of these major areas is highlighted in this special issue. The unrelenting drive to shorter lengthscales in microelectronics presents new challenges in control of chemical and physical processes at molecular dimensions. Three papers highlight recent advances understanding and controlling these processes. One paper focuses on characterization of the complex interplay of chemistry and transport for photoresist development. Another paper focuses on high-performance mold materials for nanoimprint lithography. The fi nal paper highlights progress in identifying the potential limits and power of self-assembled nanoscale patterns with block copolymer thin films. Much of the work the Polymers Division does revolves around development of new and powerful characterization techniques. Several papers highlight advances following this theme. Surface wrinkling has been developed in the Polymers Division as a tool for making very sensitive rheological measurements of thin and ultrathin polymer membranes; we include a review of this topic. Also represented is pioneering work in the Division on interfacial rheological characterization of small volume liquid samples, characterization and separation of carbon nanotube dispersions, use of combinatorial methods to characterize interactions of mammalian cells with polymeric materials, and new conceptual approaches to understanding initial cell morphological response to polymeric surfaces. We hope you enjoy the issue. More information about the Division and its programs can be found at http://www.nist.gov/mml/polymers/.

A Resolution Enhancement Material for 193-nm Lithography Comprising 2-Hydroxybenzyl Alcohol and Poly(vinyl alcohol) with Uniform Resist Pattern Shrinkage

A series of resolution enhancement materials (REMs) for 193-nm resist employing poly(vinyl alcohol), 2-hydroxybenzyl alcohol (2HBA), and a non-ionic surfactant have been prepared and evaluated. The resolution enhancement has been achieved by resist pattern thickening (pattern space shrinkage) that is caused by the interaction between REMs and 193-nm resists. The key component, 2HBA, demonstrated the capability of shrinkage of the printed spaces or holes on 193-nm resists without a cross-linking reaction. This system expanded the process margin and minimized the dependence of resist pattern sizes, pitches, and shapes in the shrinkage reaction that had been one of the critical issues in the cross-linking-type chemically shrinking materials. The optimized REM afforded about 10 to 15-nm shrinkage for hole, trench, and lines and spaces (L/S) patterns with various pitches that was suitable for advanced Logic LSI application.

Development of Ultraviolet Crosslinking Glucose-Based Resist Materials for Advanced Electronic Device Applications Using Nanoimprint Lithography

An ultraviolet crosslinking glucose-based resist material in nanoimprint lithography was studied for environmental applicability and 65 nm dense line patterning. In this study, the applyication of a glucose derivative as an ecofriendlier compound to the resist material in an advanced nanopatterning process was demonstrated. It was found that the developed glucose-based resist material with an epoxy group in cationic polymerization had the properties of high-crosslinked polymer networks for step and flash nanoimprint lithography and created 65 nm rectangular dense line patterns. In addition, an elemental analysis was carried out to evaluate resist material shrinkage in ultraviolet irradiation and the resistance of a crosslinked film. This desirable concept using a glucose derivative with an epoxy group in the resist material is one of the most promising processes ready to be incorporated into the mass production of advanced electronic device applications.

Fabrication and application of high quality poly(dimethylsiloxane) stamps by gamma ray irradiation

Poly(dimethylsiloxane) (PDMS) is the most widely used stamp material in soft lithography. Usually, it is thermally vulcanized and can't satisfy all the demands of the resolution, purity and solvent compatibility. In this work, high energy gamma rays are used to crosslink the PDMS base to fabricate stamps designed for soft lithography without the use of a catalyst. PDMS stamps fabricated in this way have several advantages including high resolution, purity and solvent resistance. The PDMS stamp crosslinked at an absorbed dose of 800 kGy has a roughness of 0.18 nm in blank area and can replicate features with the height of 1.1 nm. The amount of uncrosslinked molecules in the bulk of the stamp is only half of that of the ‘standard’ stamp (made by Sylgard™ 184 at the base/cure agent ratio of 10). Furthermore, the shear elastic modulus of stamps made by radiation induced crosslinking increases with the absorbed dose in the range of 400 kGy to 800 kGy and is higher than that of ‘standard’ stamps. By measuring the glass transition temperature and calculating molecular weights between crosslinkers, we conclude that the enhancement of stamps' quality can be ascribed to the increase of crosslinking density under gamma ray irradiation.

Development of a New Series of Self-Assembling Lithographic Materials Based on Silsesquioxane-Containing Block Copolymers

<b>Development of a New Series of Self-Assembling Lithographic Materials </b><b>Based on Silsesquioxane-Containing Block Copolymers </b>

无机激光热刻蚀材料的研究进展

无机激光热刻蚀材料的研究进展

Recent Developments in the Fabrication of Ordered Nanostructure Arrays Based on Nanosphere Lithography

Since it was invented two decades ago, Nanosphere Lithography (NSL) has been widely studied as a low cost and flexible technique to fabricate nanostructures. Based on the registered patents and some selected papers, this review will discuss recent developments of different NSL strategies for the fabrication of ordered nanostructure arrays. The mechanism of self-assembly process and the techniques for preparing the self-assembled nanosphere template are first briefly introduced. The nanosphere templates are used either as shadow masks or as moulds for pattern transfer. Much more work now combines NSL with other lithographic techniques and material growth methods to form novel nanostructures of complex shape or various materials. Hence, this review finally gives a discussion on some future directions in NSL study.

Materials for Optical Lithography Tool Application

This review of materials development for optical lithography covers two areas: materials for optical steppers and scanners, and materials for EUV lithography. In the former, materials development for advanced immersion lenses and for high-index immersion lens is discussed, whereas in the latter, materials used in multilayer EUV mirrors and to generate EUV photons are discussed.

Nanoimprint Lithography Materials Development for Semiconductor Device Fabrication

The term nanoimprint lithography (NIL) describes a number of processes used to form nanoscale structures by molding or embossing. Step and flash imprint lithography (S-FIL, a trademark of Molecular Imprints, Inc.) is a variant of NIL that can be performed at room temperature and low pressure. In S-FIL, a low-viscosity liquid imprint material is hardened in a patterned template by exposure to UV light. S-FIL is ideally suited to integrated-circuit device fabrication. Materials development for S-FIL has progressed significantly since its introduction in 1999. We discuss the status of materials development, with specific emphasis on the imprint material and functional materials, template fabrication and release layers, and S-FIL process variations.

Orthogonal Patterning of PEDOT:PSS for Organic Electronics using Hydrofluoroether Solvents

2009 WILEY-VCH Verlag Gmb Organic electronics is an emerging technology opening new opportunities in the field of large-area electronics. It has received enormous attention as a technology platform that enables flexible, large-scale devices by exploiting the unique properties of organic materials. In addition, organic electronics offer the possibility of affordable manufacture of devices through solution processing of active materials. Before this vision is realized, several challenges must be overcome, in particular the issues of patterning. Patterning of electronic materials enables microscale device structures to be defined for organic light-emitting diode (OLED) displays and organic thin-film transistors (OTFTs). In addition, patterning enhances the device performance by preventing cross-talk, increases transconductance, and prevents high off-currents in transistor arrays or drivers. The patterning of organic materials has been demonstrated by many different methods, including ink-jet printing, vapor deposition through shadow masks, soft and hard imprint lithography, and photolithography. Ink-jet printing boasts continuous roll-to-roll process capabilities and is the patterning technique of choice for polymeric materials. However, the resolution is limited to approximately 10–20mm. Shadow mask deposition is the dominant technique for small-molecule patterning, but also has notable resolution limitations. A shadow mask feature resolution is typically 25–30mm, although special masks have shown resolution down to 5mm. Shadow-mask deposition also requires a high-vacuum environment, which can introduce further limitations. Imprint lithography has demonstrated promising results, showing feature resolution down to 10 nm. However, this technique has shown only limited applicability with respect to materials and device architectures. Furthermore, in all of the aforementioned methods, registration is an issue that renders fabrication of multilayer devices exceptionally challenging. Multilayered device architecture will be essential to achieve fully integrated circuits. Photolithography, in contrast, is a widely applicable patterning method that consistently achieves both high-resolution and registration. Photolithography has the added advantage of being the most developed patterning technology and the patterning method of choice for the current semiconductor industry. In spite of the proven technical advantages, conventional photolithography has not been recognized as a suitable technique for patterning organic electronic materials. It is presently hindered by concerns of chemical deterioration of active organic materials upon exposure to process solvents for lithography. By introducing a new set of benign processes that involve new specially tailored photopolymers, we show that this problem can be circumvented. Recently, we identified hydrofluoroethers (HFEs), a family of nontoxic and environmentally friendly solvents, as being chemically benign to nonfluorinated organic electronic materials. Not only are they benign, but HFEs are orthogonal solvents to many organic compounds, that is, the organic compounds are insoluble and are not swollen in HFEs. This is a particularly useful property in the fabrication of multilevel devices, since new layers can be added without damage to existing ones. Our challenge was, therefore, to develop compatible lithographic materials for these new process solvents. By employing a fluorinated photoresist compatible with HFEs, we demonstrate sub-micrometer photolithographic patterning of organic electronic materials. Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is a mechanically flexible, transparent, and highly conductive polymer blend, which has found various applications in organic electronics including serving as the electrode material for plastic substrates, because of its low-temperature processing requirements, and as charge-injection/-extraction layers in OLEDs and photovoltaic devices. However, photolithographic patterning of PEDOT:PSS for device components is not straightforward, because i) PEDOT:PSS films are damaged by aqueous solutions, which are standard developers in conventional photolithography, and ii) acid-sensitive photoresists are adversely affected by the acidic PEDOT:PSS. In this communication,wepresent a unique acid-stable imaging material for PEDOT:PSS and organic electronic materials in general. We report on the sub-micrometer patterning of PEDOT:PSS films and their subsequent application to the fabrication of a field-effect transistor, in which an organic semiconductor material, pentacene, is patterned by the same protocol. In designing a HFE-compatible photoresist, it was most important that the photoresist be soluble in fluorous solvents. In general, fluorous solvents dissolve highly fluorinated materials. The copolymer 3, derived from the highly fluorinated monomer 1 and photolabile monomer 2, was expected to yield a material that exhibits a solubility switch following UV irradiation

Molecular Dynamics Study of Nanoimprint Lithography for Glass Materials

Molecular dynamics studies are carried out to investigate the deformation mechanism of glass materials for nanoimprint lithography (NIL). The filling process of glass into the mold cavity and the stick slip phenomena during the mold release are investigated in atomic scale. The relationship between displacement of the mold and applied pressure to the mold are evaluated in NIL including both deformation and demolding processes. The dependence of the required pressure for full filling on the glass thickness and the line width of the mold cavity are investigated. In addition, fracture of glass pattern during the mold release is studied.

Towards X-ray induced transient grating methods for nanometer scale dynamics: Diffraction on transient structures induced by extreme ultraviolet radiation from FLASH

Using the high brilliance femtosecond soft X-ray pulses from the Free-Electron LASer at Hamburg (FLASH) the X-ray induced transient optical reflectivity change of GaAs has been established as a versatile method for femtosecond X-ray/optical cross-correlation [1]. As the underlying physical mechanism is the X-ray induced dynamics within solids, we present in this work a feasibility study how transient grating methods could be used to study nanometer scale dynamics in materials, such as the radical diffusion parameters in photoresist materials for EUV lithography.

Alkanethiolate Self-Assembled Monolayers As a Negative or Positive Resist for Electron Lithography

Taking self-assembled monolayers (SAMs) of octadecanethiol (ODT) on Au(111) as a test system, we demonstrate that aliphatic SAMs can serve as both positive and negative resist materials for electron-beam lithography. This is a principally new finding, since these systems are generally considered as positive resists only and no negative resist behavior has been reported so far. The behavior of the SAM resist was found to be dependent on the irradiation dose and explained by the dominance of different irradiation-induced processes at different stages of electron-beam treatment. A negative resist performance was only observed at low irradiation doses. The transition from the negative to positive resist behavior occurred at 8−10 mC/cm2 (50 eV electrons) under the conditions of our experiments.