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Laser-based pattern generators are versatile tools for transferring design layouts into resist structures. The non-linear response and the proximity effects caused by the interaction of the laser beam with the low-contrast photoresist are particularly critical for the creation of shapes with sloped, stepped and continuous topographies. Cross-sections were taken to compare topological differences of the measurement results with the graytone design. For simple shapes, an iterative adjustment of the global dose distribution is sufficient, while for more complex shapes the local correction of dose values using mathematical models is preferred. For the one-step exposure of the corrected map, it requires the careful assessment of a contrast curve and knowledge of various parameters. The coefficient of determination R2 as a unitless single figure of merit proved useful in the quantitative comparison of the two methods, and demonstrated the capability of current model-based approaches for shape optimization towards the target design within one cycle.

Recently chalcogenide phase-change resist Ge 2 Sb 2(1− x ) Bi 2 x Te 5 , which is compatible in next generation full-vacuum microelectronic manufacturing, has been paid much more attention due to the its excellent properties, such as high etching selectivity between Si and Ge 2 Sb 2(1− x ) Bi 2 x Te 5 (about 500), wide spectral absorption and able to be prepared in vacuum. However, the very low developing selectivity (lower than 5) between its crystalline and amorphous phase limits its application in lithography. Here we developed a novel high-selective developing method to significantly improve the selectivity up to 22 (5 times than before), which enables the inorganic resist to be workability. Moreover, the developing mechanism is revealed, and this is helpful to dry developing technology of Ge 2 Sb 2(1− x ) Bi 2 x Te 5 . [ABSTRACT FROM AUTHOR]

A positive tone resist for UV and X-ray lithography synthesized starting from an organically modified silicon alkoxide, bis(triethoxysilyl)benzene, through the sol-gel method, either in basic or in acid catalysis, is presented. Being directly photo-processable, the sol-gel system combines the opportunity to avoid the use of a sacrificial layer in the fabrication process, with the possibility to fit electro-optical and structural properties of the final device material to specific requirements. In addition, the positive tone behaviour allows to preserve the organic functionality of the system after irradiation. A study of the optical and structural modifications induced on the resist by irradiation has been carried out by FT-IR spectroscopy, UV-vis spectroscopy and spectroscopic ellipsometry. An interpretation of the mechanisms leading to exposed cross-linked film development is given. Experiments have demonstrated the possibility of obtaining structures on films with lateral dimensions spanning from the micron scale up to less than a hundred nm, opening the way to a possible exploitation of such positive tone functional system in the field of miniaturized sensors. [ABSTRACT FROM AUTHOR]

Abstract: Natively porous hybrid organic–inorganic sol–gel systems have been engineered to be used as functional positive photoresists, aimed to the realization of microsensors in a single-step process. Interesting results have been obtained combing three main sol–gel system features: the direct patternability through X-ray lithography, being processable without the addition of a photocatalyst; the functionalizability, properly designing the organic component of the hybrid network or incorporating active species; the open micro or mesoporosity, tailored by the synthesis process and precursor choice. The photoprocessable porous films have been synthesized starting from a Bridged Polysilsesquioxane (BPS) precursor, 1,4-bis(triethoxysilyl)benzene. The correlation between chemical properties of the sol–gel material and its patternability is described in detail. X-ray exposure leads to a progressive alkyl and aromatic compound elimination and promotes inorganic condensation in the system, allowing the selective dissolution of irradiated cross-linked films in suitable etchants. Patterns of final resolution lower than 100nm have been realized on BPS-based films synthesized in acid conditions, a procedure that allows to take advantage of a straightforward embedding protocol for active species in the sol–gel matrix. The BPS-based system has been doped with a covalently linked quinolinium dye, obtaining thin sensing films patternable by X-ray lithography. A feasibility test for the fabrication of optical microdevices, where fluorescence properties are obtained directly on the patterned coatings, has been provided. [Copyright &y& Elsevier]

Well-defined norbornene–lactone-functionalized polymers were synthesized by atom transfer radical polymerization (ATRP) of 5-methacryloxy-6-hydroxynorbornene-2-carboxylic-6-lactone (MNL) and 5-acryloxy-6-hydroxynorbornene-2-carboxylic-6-lactone (ANL) monomers. The ATRP of MNL initiated by ethyl 2-bromopropionate (EBrP), in both N, N-dimethylformamide (DMF) and o-dichlorobenzene (ODCB) solvents was successfully carried out in the presence of CuCl/CuBr and N,N,N′′,N′′,N′′-pentamethyltriethylenetetramine (PMDETA) at 70 °C. The CuCl/ODCB catalyst system gave rise to a lower Mw/ Mn (≦1.20) than CuBr/DMF catalyst system. The ATRP of ANL was feasible in the presence of CuBr and PMDETA at 70 °C but showed lower reactivity than MNL. The resulting polymers were characterized by means of gel permeation chromatography (GPC) and 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

For deep ultraviolet (DUV) light, a low-absorption acrylic copolymer was developed and could be able to substitute Novolak resin for DNQ/Novolak photo resist (PR) material. The acrylic copolymer was synthesized by using methacrylic acid (MAA), 2-hydroxyethyl methacrylate (2-HEMA) and a 3,3,5-trimethyl cyclohexyl methacrylate (TMCHMA, stereo-nonaromatic monomer) so as to be used as a binder of the photo resist material. Tricyclo[5,2,1,02,6]decanedimethanol (TDMol) and 1,2-napthoquione-2-diazido-5-sulfonyl chloride (5-NDSC) together composed the photo active compound (PAC). Then, the binder and the PAC were mixed to acquire a new type of photo resist. [Copyright &y& Elsevier]

A positive chemical amplification resist based on acid-catalyzed fragmentation of the acetal groups in the polymer main-chain has been developed for electron-beam (EB) nanolithography. This resist consists of an acid generator, an acid-diffusion controller and an acid-breakable (AB) resin that is synthesized through a co-condensation reaction between polyphenol and aromatic multi-functional vinylether compound. Despite a large difference in the molecular weight distribution of the AB resins, the AB resin-based resists (ABRs) provide high-resolution patterns (60-nm line-and-spaces) with high sensitivity (<10 μC/cm2 at 30 kV). AFM analysis showed the surface roughness for ABR is less than half (RMS: ∼1 nm) compared with that for novolak resin-based resist. By using ABR, the sub-100 nm L/S patterns with line-edge roughness (3σ) about 5 nm are obtained. [Copyright &y& Elsevier]

The performance of a positive tone resist, PMMA, for sub 100 nm patterning of nano-dots using electron beam lithography is to be studied. This optimization is done on a JEOL JBX-6000 FS System. The various parameters such as beam current, resist thickness, dose and electron energies are optimized. This patterning involves greater control over beam parameters so as to reduce aberrations that might arise due to astigmatism. In this respect, the optimization of the beam current parameters is very important, as a narrower beam will minimize scattering effects. These structures will be particularly significant for the fabrication of quantum dot based devices. Nano-dot arrays of dimensions 70 nm with equal spacings of 70 nm were obtained at 100 pA beam current at 50 KeV for a dose of 170 μC/cm2. [ABSTRACT FROM AUTHOR]