In the last decade, major advances in fabricating electronic devices have placed increasing demands on microlithography, the technology used to generate today's integrated circuits. Within the next few years, a new form of lithography will be required that routinely produces features of less than 0.1 μ. As the exposing wavelength of light decreases to facilitate higher resolution imaging, the opacity of traditional materials precludes their use; and major research efforts to develop alternate materials are underway. Through understanding of materials structure and its relationship to device process requirements and performance, cycloolefin based polymers provide for sub-0.1 μm imaging capability using 193 nm exposure. Alicyclic monomers such as norbornene are readily copolymerized with other units to afford a wide range of alternative matrices that exhibit transparency at the exposing wavelength and aqueous base solubility. Further reduction in imaging wavelength necessitates renewed research to define alternative materials platforms. Materials transparency is the key issue to be addressed for 157 nm or EUV lithography. Novel polymer architectures including fluorinated polymers will be required to effect sufficient transparency coupled with requisite solubility, sensitivity, contrast etching resistance, shelf life and purity. Each of these issues will be discussed from the perspective of polymer materials chemistry.

Spectroscopic ellipsometry is one of the most important tools for thin film metrology. It is now intensively used in microelectronics and especially for the microlithographic applications. Instrumentation for the next generation of VUV lithography at 157nm requires special optical setup since oxygen and water are extremely absorbing below 190nm. Recently a new ellipsometer included in a purged glove box to reduce the oxygen and water contamination in the part per million range has been developed. In the VUV range, roughness and interface diffusion become critical since the layer thickness is generally reduced. An independent characterization technique like the grazing x-ray reflectance is then extremely complementary to ellipsometry in this wavelength region. The present paper presents recent results on up to date lithography samples combining the two characterization techniques. Photoresists and gate dielectrics are successively examined.

The SIA roadmap predicts mass production of sub-100 nm resolution circuits by 2006. This not only imposes major constraints on next generation lithographic tools but also requires that new resists capable of accommodating such a high resolution be synthesized and developed concurrently. Except for ion beam lithography, DUV, X-ray, and in particular electron beam lithography suffer significantly from proximity effects, leading to severe degradation of resolution in classical resists. We report a new class of resists based on organic/inorganic nanocomposites having a structure that reduces the proximity effects. Synthetic routes are described for a ZEP520®nano-SiO2 resist where 47nm wide lines have been written with a 40 nm diameter, 20 keV electron beam at no sensitivity cost. Other resist systems based on polyhedral oligosilsesquioxane copolymerized with MMA, TBMA, MMA and a proprietary PAG are also presented. These nanocomposite resists suitable for DUV and electron beam lithography show enhancement in both contrast and RIE resistance in oxygen. Tentative mechanisms responsible for proximity effect reduction are also discussed.

We developed a new method for easy fabrication of micrometer-scale fine metal patterns on substrates. The patterns can be fabricated at low cost, at low processing temperature, and on uneven substrates as well as on plane surfaces. The method involves, first, forming hydrophilic and hydrophobic patterns on the substrates, and, second, depositing metal by electroless plating on the hydrophilic area. Hydrophilic and hydrophobic patterns were formed on a sensitizer containing naphthoquinonediazide (NQD) units coated on the substrates by the exposure. In the exposed areas, metal particles that are catalysts for electroless copper plating were adsorbed in the ion-exchange reaction and then the reduction treatment was performed. Copper was selectively deposited by the self-catalyst mechanism, according to the exposed patterns. All experimental processes can be carried out at room temperature. Using this new method, copper line patterns of 25 μm and copper dot patterns of 15 μm diameter were fabricated on the substrate.

We have demonstrated that well-dispersed sub-micron chromium oxide particles can be fabricated by laser-induced solution deposition (LISD) from the solution of CrCl2 solute dissolved in organic solvents containing THF and cyclohexane. The particles are uniform in composition and contain little contamination. The distribution of the particles is narrow in three sizes: 230 nm, 350 nm and 400 nm. We have discussed the kinetics of forming these three kinds of sub-micron particles and the difficulty in obtaining single-phase chromium oxide. We have successfully shown that LISD is a unique technique for fabricating submicron chromium oxide particles with uniform composition and controllable size with narrow particle size distribution. The kinetics (nucleation and growth mechanism) of forming three sizes of particles is discussed.

We demonstrate the focusing action of a compact solid state pixelated Fresnel phase (PFP) lens for electrons (700 nm in diameter), consisting of an array of holes (“pixelated”) directly drilled by a finely focused electron beam in a thin AlF3 thin film on carbon supporting film. The depths of holes, hence the phase of the exit electron wave is varied as a function of radius from the center of the pattern so that the wavelet from each hole can be in phase on axis at a designated focal point thus producing a lens. An array of two types of lenses, convergent and divergent, with nominal focal length of 1 mm for 200 keV electrons was produced. The estimated full-width-half-maximum of the focus is 8 nm. With improvement of the efficiency, these lenses may find applications in parallel electron-beam lithography, in X-ray optics and in light optics.

We use a layer-by layer electrostatic assembly technique to obtain aggregates of a chromonic mesogenic dye on mica substrates. The aqueous solutions of dye used for deposition are in the nematic phase. Atomic force microscopy of the dried films reveals that the chromonic molecules adsorb at the charged substrate in the form of ordered aggregates of elongated shape. These elongated aggregates form orientationally ordered arrays. The overall orientation of the array can be changed by shear.

Cyclic voltammetry (CV) was used to study the reduction potentials of 2,5-di(ethynylphenyl)-4-nitroaniline and 2,5-di(ethynylphenyl)nitrobenzene. Although no absolute reduction potentials can be used in the correlation between solution (CV) and solid state (nanopore) embodiments, each CV plot showed two reductions. The first and second reduction might correspond to switching events of recently reported molecular electronic devices in a nanopore. Cyclic voltammetry results are also reported for other potential molecular scale electronic devices.

Unimolecular rectification, previously reported between oxide-bearing electrodes, was detected between oxide-free Au electrodes for a Langmuir-Blodgett monolayer of the zwitterionic D+-π-A− molecule hexadecylquinolinium tricyanoquinodimethanide, C16H33Q-3CNQ. The top gold electrode was deposited from a Au vapor pre-cooled by multiple collisions with Ar atoms. The maximum rectification ratio is 27.5 at 2.2 Volts (the average rectification ratio is 7.55). The currents are as large as 9.04 × 104 electrons molecule−1 s−1. The result reinforces previous work with oxide-bearing Al electrodes, but the currents with Au electrodes are larger by three to five orders of magnitude.

We describe recent experiments in which we attempted the initial steps for fabricating twodimensional arrays of metal nanocrystals. We use a commercial pulsed-laser deposition system in concert with a focused ion beam to attempt control over both lateral and vertical dimensions at the nanometer length scale. In our experiments, regular arrays of holes typically 80 nm in diameter were drilled in Si substrates using the focused ion beam. Silver atoms were then deposited onto these substrates by pulsed laser evaporation from a metallic target in high vacuum. Under certain conditions of substrate temperature, laser pulse repetition rate, and fluence, small silver nanoclusters form preferentially around the structures previously etched in the silicon surfaces by the focused ion beam.