Bi nanolines, which self-assemble on Si(001), have been used as templates for the deposition of a variety of metals: noble metals, transition metals, and Gr. III metals. The different metals show a variety of behaviours on this surface, from a strong interaction in the case of In and Al, to a very weak interaction in the case of Ag. The different phenomena are discussed in terms of a balance of different competing surface mechanisms, such as diffusion and nucleation, which drives the observed behaviours.

Nanoelectrode lithography is a pattern duplication method which combine template and electrochemical reaction. With the nanoelectrode lithography, electrochemical reaction occurs along with the conductive area of the template, and oxide pattern can be directly fabricated on a surface of semiconductor or metal layer. This "Resist-less patterning" method may have advantage for precise patterning in the future.

Electrodeposition has emerged as a novel economically viable technique with large-scale production capabilities in modern day micro technologies. The current trends are to extend the potential of the electrodeposition to nano fabrication. We have successfully electrodeposited Cu/Co multilayers, exhibiting appreciably high GMR, on ITO as well as on Cu/Si substrates. Multilayer stacks with films in thickness range 1 – 10 nm were deposited. The Co layers have different mechanisms of growth on these substrates, thus resulting in different microstructure and topography of the electrodeposited films. This leads to different GMR behavior of the multilayers in both these cases. Room temperature GMR values of 15% at low fields are obtained on ITO substrate and higher values are possible on Cu/Si substrate.

GMR current-in-plane (CIP) spin valves are currently used in production of high density recording heads. For the next generation of heads, with recording densities higher than 100 billion bits per square inch (Gbpsi), confined-current-path (CCP), current- perpendicular-plane (CPP) GMR heads are the subject of intensive study. For the CPP stack, thick (150 nm) Cu leads are required to minimize the potential drop across the leads. This often leads to a rough film surface in the bottom lead which translates up into the GMR stack, thereby reducing the GMR effect because of roughening of the interfaces. Thick bottom leads also have large average grain sizes, leading to an increase in the coercivity of the ferromagnetic layers deposited on top of these leads. In order to decrease the grain size and roughness of the bottom Cu lead, lamination of the thick (150 nm) Cu with Ta interlayers was carried out, keeping the total Cu and Ta thicknesses constant. As the number of Ta-Cu bilayers was increased, the roughness decreased significantly. It was observed that the roughness decreased from over 1 nm for a single bilayer to about 0.3 nm for 10 bilayers. Atomic force microscopy (AFM) was used to determine the roughness of the samples and in-plane grain size. Scanning electron microscopy was used to confirm the in-plane grain size. X-ray diffraction was used to analyze the out-of-plane grain size of the Cu/Ta laminates. Cross-sectional transmission electron microscopy (TEM) was also utilized to analyze the interface quality. An increase in the resistance of the laminated lead was seen with increase in the number of laminations. This undesirable side effect can be minimized by improvement of the base vacuum of the sputter system, deposition at relatively high rates, and reduction of the latency time between successive film depositions. The in-plane film stress was also studied as a function of lamination frequency, and found constant for the same total thickness of Ta and Cu, as expected. The coercivity of Co90Fe10 layers deposited over laminated Cu/Ta leads was seen to decrease with increasing lamination frequency, also as expected. An even stronger effect on the CoFe coercivity was produced by using a 5nm Ta layer to cap the thick Cu lead, yielding significantly lower coercivity

We have developed a simple and fast methodology to control the orientation of cylindrical microdomains in thin block copolymer films under controlled atmosphere conditions. Asymmetric block copolymers of polystyrene and poly(ethylene oxide) (PS-b-PEO) were dissolved in toluene and spin coated with less than one minute exposure to different solvent vapors and controlled humidity. The specific choice of solvents was based on the polymer solubility parameters and the solvent vapor pressure. By controlling the spin coating environment we were able to produce cylinders with orientations ranging from parallel to perpendicular with respect to the substrate. Orientation was apparently controlled by the preferential affinity of the vapor atmosphere. A combinatorial gradient technique was employed to investigate the mechanism of solvent-induced microdomain orientation.

In order to enhance the photosensitivity of photoreactive materials utilizing base-catalyzed reactions, we developed base amplifiers that decompose autocatalytically to generate newborn amine molecules. Actually, we reported that the addition of base amplifiers to the photoreactive materials such as photoresists and UV-curing materials resulted in the marked improvement photosensitivity. However, conventional base amplifiers have aromatic rings such as fluorenyl groups and phenyl groups. Consequently, these base amplifiers have strong absorption of UV light which is a trigger of photolysis of a photobase generator. This leads to the hindrance of the photolysis. We report here novel base amplifiers with 3-nitropentan-2-yl group which has no aromatic rings.

The base amplifiers decomposed autocatalytically to generate newborn amine molecules at an elevated temperature in solution and a polystyrene film in the presence of a catalytic amount of amines. Moreover, combining the base amplifiers with UV-curing materials consisting of a photobase generator and liquid epoxy resins resulted in the improvement of curing efficiency. To apply the base amplifier to photopatterning materials, we synthesized novel silicone resins with 3-nitropentan-2-yl groups as base-amplifying polymers. A film of the resin decomposed autocatalytically to generate amino groups in its side chains at an elevated temperature in the presence of a catalytic amount of amines. Furthermore, we demonstrated that the resins sensitized with a photobase generator provided negative- and positive-working photopolymers in the following ways. A thin film of the resin containing 10 wt% of a photobase generator became soluble in an acidic aqueous solution after 254 nm light irradiation of an exposure dose of 1 mJ/cm2 and subsequent baking at 50 oC for 20 min. This is because of formation of amino groups in its side chains. On the other hand, the film became insoluble in organic solvents after 254 nm light irradiation of an exposure dose of 1 mJ/cm2 and subsequent heat treatment at 50 oC for 40 min, this arises from that the photobase-catalyzed hydrolytic condensation of residual ethoxysilyl units of the resin proceeded to form crosslinked networks.

Recently, the development of information technology (IT) increases the demands of memory devices. Phase change random access memory (PRAM), based on the reversible phase change of the chalcogenide alloy, Ge2Sb2Te5, is widely regarded as a favourite candidate for the next generation memory. Because of PRAM has a simple cell structure with high scalability; it is non-volatile, has a relatively high read/write operation speed (Â50ns). The PRAM operation relies on the fact that chalcogenide-based materials can be reversible switched from an amorphous phase to a crystalline state by an external electrical current. It is important to study the electrical property with set/reset cycles, since film thickness shrinkage occurs with the phase transition.

In this work, we fabricated the 100nm amorphous Ge2Sb2Te5 thin film on TiN/Ti/Si substrate using dc-magnetron sputtering. The 50X50§2 isolated Ge2Sb2Te5 cell was lithographed by the lift-off pattern and wet etching. And TiN top electrode was deposited using pattern align process at room temperature after the SiO2 insulator CMP. Phase transition behavior with the set/reset cycle was observed using I-V measurement and transmission electron microscope (TEM) on isolated Ge2Sb2Te5 cell. The set/reset programming was operated using tungsten SPM tip which was fabricated using focused ion beam (FIB) lithography. I-V curve which was observed by the I-V probe clearly showed that the phase transition was occurred by applying the electric field through the I-V probe. The resistivity difference between amorphous and crystal state was more than 102. After the phase transition, it was also demonstrated with transmission electron microscope (TEM) analysis. For the preparation of TEM specimen of the amorphous and crystalline cell, focused ion beam (FIB) lithography was adopted.

The development of periodic nanostructures fabricated by self-assembly of surfactants and block co-polymers has opened up the possibility of generating periodic magnetic nanostructures of types not accessible by self-assembly of nano-particles. The fabrication of mesoporous silica thin films around self-assembled block co-polymers is well established. Common structures for such films are SBA-15 which consists of hexagonal arrays of cylindrical pores and SBA-16 which has face centered arrays of spherical voids. These pores are connected by 1-2 nm thick flaws in the continuous silica phase producing an effectively continuous porous phase. After removal of the block co-polymer template, electrodeposition into the mesoporous silica thin films produces arrays of 5-10 nm diameter nano-wires and nano-particles. We have demonstrated that such materials can be fabricated on a wide range of metal substrates. Characterization by Scanning Electron Microscopies shows that the mesoporous silica is well ordered over micron scale areas. Grazing Incidence Small Angle X-ray Scattering (GISAXS) studies shows diffraction spots, consistent with the entire film being well ordered. GISAXS also shows that the mesoporous silica films survive removal of the template and electrodeposition of nickel and cobalt into the mesoporous silica films. Such films are of interest for their magnetic properties, as the nanophase and scale can be independently varied. Further, the presence of nanowires inside an insulator suggests that these films might also be of interest as the current confining element for Confined Current Path-Current Perpendicular to Plane GMR sensors.

Block copolymers that self-organize are of interest as templates for patterned media, as they potentially provide a low cost fabrication route. Poly(styrene)-Poly(methylmethacrylate) block co-polymers (PS-b-PMMA) of appropriate block length and PS to PMMA ratio self-assemble into a 2-D hexagonal phase in which the PS majority phase is continuous and surrounds cylinders of the minority, PMMA phase. For application of this phase to patterned media it is necessary that the cylinders of the minority phase be oriented perpendicular to the substrate surface. This can be achieved by a number of methods, including appropriate choice of substrate and use of a random co-polymer underlayer. Appropriate substrates include H-terminated silicon, some carbon coatings and some ITO glasses. Use of an acetic acid wash causes the minority PMMA component can be induced to be rearranged, giving rise to pores perpendicular to the substrate. Electrodeposition of a metal into the pores produces a hardmask which can be used with ion-milling to transfer the block co-polymer pattern onto a magnetic thin film.

Low density Sn doped resorcinol formaldehyde aerogels were fabricated for extreme ultraviolet (EUV) source emission lithography experiments (EUVL). EUVL is a candidate to succeed conventional optical lithography. EUVL requires a reliable emission (13.5 nm) source. One type of source is a laser-produced plasma. Several laser-plasma source materials have been considered such as lithium, xenon and tin. Tin is considered ideal because it has a high conversion effeciency. However, solid tin targets create a large quantity of debris which can damage the optics of the laser system. As a solution to this problem, we minimized the amount of tin by dispersing it in a low density resorcinol formaldehyde (R/F) matrix. These targets were fabricated into small spheres using the microencapsulation method. Initial experimental results show that these targets yield a similar intensity in the EUV regime when compred to a full density Sn target.

Electrically induced quasi-permanent changes in low-field conductivity have been observed in single crystals of LaGa1-xMnxO3 in the broad range of Mn ion concentrations. The memory effects can last for a long time at room temperature and can be easily erased by heating up to Tc ∼300 C. The temperature dependence of the resistivity has a sharp drop around the phase transformation temperature, pointing to the role of phase transformation processes. The switching between high resistance and low resistance states is demonstrated. We explain our experimental data in terms of thermo induced local phase transition with the oxidation of Mn ions. The results of the ab initio calculations of the electron energy structure in Jahn-Teller-distorted and non-distorted cells confirm the mechanism suggested.

The hot embossing of grating-based optically variable devices has been demonstrated in biaxially-oriented polypropylene (BOPP). The embossing of several types of optically variable device has been examined including portrait, non-portrait and 3 dimensional images. The images embossed into BOPP have displayed a novel optically variable effect when viewed in transmitted light. Embossing of the grating structures was examined over a range of temperatures (80-155 °C) at 135 kN force. High quality replication was achieved over a full embossing area of 80 x 80 mm at temperatures > 120 °C.

Pattern size and pitch are two major factors that directly affect the capacity of a data storage unit. Electron beam lithography, because it can be used for direct writing at the nanometer scale, is one of the potential candidates to fabricate ultra-fine and ultra-compact patterns for the next generation of data storage media.

In the paper, we present methods to reduce the pattern size and pitch written by electron beam on positive tone resist Poly(methylmethacrylate) (PMMA). The first method uses a writing dose which is much lower than the critical dose of the PMMA. However, in this technique, the distance between the adjacent writing spots (which are approximately Gaussian in spatial extent) is finely adjusted until the partially overlapping Gaussian functions form a contour with periodic dose peaks higher than the critical dose. This overlapping exposure results in a periodic exposure of the PMMA. Most importantly, this writing strategy, using the overlapping of low dose Gaussian beams, results in patterns with smaller size and pitch compared to the conventional methods that use a higher writing dose than the critical dose. To further improve the results, we use ultrasonic development in combination with cold development to greatly increase the resist contrast. The increased contrast results in smaller pattern sizes, and enables smaller pattern pitches, as well as improving pattern uniformity and reproducibility.

Finally, as a demonstration of the technique using a conventional beam voltage of 15kV, we achieve ultra-fine and high density patterns with ∼10nm linewidths and 50nm in pitch, which corresponds to a storage capacity near 200 billion bits/inch2. In comparison, standard techniques (using a dose slightly higher than the critical dose and normal development strategy), we can only obtain patterns with linewidths of about 20-30nm and pitch of about 100nm.

The Step and Flash Imprint Lithography (S-FILTM) process uses field-to-field drop dispensing of UV curable liquids for step and repeat patterning for applications where high-resolution mix-and-match overlay is desired. Several applications, including patterned media, photonic crystals and wire grid polarizers, are better served by a patterning process that prints the full wafer since alignment requirements are not so stringent. In this paper, a methodology for creating high resolution thin templates for full wafer (or disk) imprinting is described. The methods have been applied toward the imprinting of both patterned media and photonic crystal devices using a large area printing tool developed around the S-FIL process. Techniques for further enhancing the pattern density as well as a method for addressing feature image placement are described. Finally, a process for replicating a Master Template is discussed in detail.

We report a single-electron transistor concept and its related process enabling the fabrication of ultrasmall junction capacitance. The method utilizes a nanodamascene approach where trenches in silicon oxide are covered with a filling material and planarized with chemical mechanical polishing. Single-electron transistors fabricated with this approach were characterized up to 433 K and demonstrated that the nanodamascene process has high resolution, is relatively simple and is highly scalable.

We calculated transport properties of edge-to-edge quantum cross structure that consists of two metal nano-ribbons having edge-to-edge configuration with a tunnel barrier and showed current-voltage characteristics depending on the metal-ribbon thickness (5-30 nm), the barrier height (0.5-1.5 eV) and the barrier thickness (0.5-1.0 nm). Interesting behavior of transport properties is that the metal-ribbon thickness affects the current density due to the quantization of nano-ribbon and also the current density, being dependent on the barrier height and the barrier thickness, decreases with high and thick barrier. These calculated results indicate that we can precisely obtain the information on the material sandwiched between two electrodes, such as the barrier height and the barrier thickness, by a fit of experimental data to our derived equation, and these approaches result in a distinction between the sandwiched material and the electrode.

Giant magnetoresistive (GMR) materials-based magnetic random access memory (MRAM) has become attractive due to non-volatility, speed and density1. The vertical MRAM (VMRAM) design model shows good signal level and high speed and density potential. The memory cell for the VMRAM model is a ring shaped magnetic material multilayer, which ensures high repeatability and low switching energy. This GMR structure, however, is difficult to pattern as it contains materials such as Ni, Fe, Co, and Cu, which are difficult to dry etch because they lack volatile etch products. This work shows that it is possible to overcome the difficulties associated with etching GMR materials by using hydrogen silsesquioxane (HSQ) as an etch mask. We have used HSQ in a direct-write electron-beam lithography system with a dose of 600 μC/cm2, and in a Ga+ ion focused ion beam (FIB) system with a dose of 12 μC/cm2. Both are followed by development and an argon plasma etch at 10mTorr and 100W RIE power. The HSQ layer provides high resolution as well as good etching resistance. Electron-beam exposed HSQ shows a 1:1.5 selectivity over the GMR film stack and the FIB exposed HSQ showed an improved etch selectivity of 1:1. Ring shaped GMR structures with a 75/225 nm (ID/OD) have been fabricated, which corresponds to a memory density of 4Gb/in2.

A new series of anionic photoacid generators (PAGs), and corresponding polymers were prepared. The thermostability of PAG bound polymers was superior to PAG blend polymers. PAG incorporated into the polymer main chain may improve acid diffusion compared with the PAG blend polymers, which was demonstrated by Extreme Ultraviolet lithography (EUVL) results: the fluorine PAG bound polymer resist gave 45 nm (1:1), 35 nm (1:2), 30 nm (1:3) and 20 nm (1:4) Line/Space as well as 50 nm (1:1) elbow patterned, showed better resolution than the blend sample.

The initial growth of non-epitaxial thin films was studied and discussed using the concept that thermodynamics controls the unit-structure within the surface diffusion length of deposits, whereas kinetics controls the ensemble-structure on a large scale. Three basic topics, growth mode (island shape), crystalline (island inner) structure, time-dependent properties of island ensemble (island size, distance, and density), are summarized based on the investigation of thin film growth of metals on TiO2, Cu on SiO2 and Ti/SiO2. This study provides fundamental understanding of structural control during thin film growth, and further can be applied to various advanced devices for electronics, photonics, catalysis, and energy applications.

Uniformity of nanoimprint lithography has been quantitatively studied through the ability to replicate regular lines arrays by wafer-to-wafer imprint. Two statistic coefficients have been defined in order to quantify the local uniformity and the ability to identically imprint two similar areas respectively. Those coefficients enable to compare different imprint profiles in terms of uniformity and to point out the efficiency of soft layers insertion into the imprint stack.