In this paper we investigate fundamental resist properties to enhance resolution and focus margin for immersion
contact hole patterning. Basic chemistry factors have been used to manipulate the iso-focal region (the region of
smallest critical dimension variation through focus) of the photoresist and study the impact on resolution and focus
margin for small isolated contact holes. Acid diffusion length is one of the key factors investigated, which can be
controlled by polymer, PAG, quencher, bake temperature and bake time. The various criteria investigated for this study
were: focus and exposure latitude for dense L/S, dense C/H and semi-dense C/H. The effect of manipulating the acid diffusion of the photoresist on imaging small contact holes was verified using ultra-high NA immersion imaging at 1.35
Recent progress in developing high-performance organic polymers for electro-optics and photonics is reviewed. A highly fluorinated hyperbranched aromatic polymer with the degree of branching around 0.51 was prepared by a mild one-step polyesterification of an AB<sub>2</sub> type monomer. Further post-functionalization with and thermally cross-linking by aromatic trifluorovinyl ethers (TFVE) afforded thermally stable, low loss optical polymer with improved solvent resistance. By more precisely controlling the molecular nano-architecture, we have developed a series of highly fluorinated crosslinkable dendrimers. These materials possess most of the desirable properties needed for the fabrication of optical waveguides, such as high solubility in common organic solvents (up to 50 wt%), very low optical loss, and excellent thermal stability. To overcome the “nonlinearity-stability tradeoff,” a facile and reversibly crosslinkable NLO polymer system is developed that combines both advantages of high poling efficiency and good alignment thermal stability. By smartly controlling the poling and crosslinking processes through the reversible Diels-Alder (DA) reactions, it allows highly polarizable chromophores to be efficiently poled at the stage of low viscosity linear thermoplastic polymer. The resulting nonlinear optical polymer exhibits a combination of a very large <i>r</i><sub>33</sub> value (76 pm/V at 1.3 μm) and good temporal stability at 70°C.
Recent progress in developing high-performance nonlinear optical chromophores and polymers for electro-optics is reviewed. Using the single-mode focused microwave irradiation, a diversified family of 2,5-dihydrofuran derivatives has been synthesized as a new class of tunable electron acceptors. Very large r33 values (128 and 116 pm/V at 1.3 μm) have been demonstrated by doping one of the 2-dicyanomethylen-3-cyano-4,5,-dimethyl-5-trifluoromethyl-2,5-dihydrofuran (CF3-TCF)-based chromophores in poly(methyl methacrylate) (PMMA) and a high T<sub>g</sub> polyquinoline (PQ-100), respectively. An excellent long-term temporal stability at 85°C has also been maintained in the PQ system. Two side-chain dendronized NLO polymers have been synthesized. Using a mild, simple, and generally applicable post-functionalization method, highly polarizable chromophores with dendritic modification has been covalently attached to side chains of poly(4-hydroxystryene). This approach provides the combined advantages of achieving better poling efficiency through the dendritic effect and shortening the development time required for E-O dendrimer synthesis. Systematic property comparison between these polymers and other conventional NLO polymers, such as guest-host and simple side-chain polymers, has been performed. Exceptionally high poling efficiency (a very large E-O coefficient of 97 pm/V at 1.3 μm) and good temporal stability at room temperature were dmeonstrated in this dendronized side-chain polymer system.
Recent development of dendron-containing NLO chromophores and polymers is summarized. By modifying the chromophore shape or applying the site isolation principle to these materials, we have systematically build up our understanding of how to molecular engineer the NLO materials. In this process, we have introduced the dentritic structures to these materials, varied from 3-D shaped dendritic chromophore, to fully-functionalized dendrimers with the center cores of NLO chromophores and crosslinkable periphery, and to side-chain dendronized NLO polymers. Compared to the conventional designed organic NLO materials, these nanoscale tailored NLO chromophores and macromolecules provide great opportunities for the simultaneous optimization of macroscopic electro-optic activity, thermal stability, and optical loss.
A wide variety of aromatic trifluorovinyl ether monomers and highly fluorinated crosslinkable dendrimers have been developed via novel synthetic strategies. Through the thermal dimerization of trifluorovinyl ether moieties on the monomers or on the periphery of dendrimers, these monomers or dendrimers can be melt or solution polymerized to form perfluorocyclobutane(PFCB)-containing prepolymers with good processability for optical waveguide fabrication. By further thermal crosslinking, the resulting thermoset materials possess low optical loss (0.3-0.4 dB/cm at 1310 nm with 1% of DR-1 or DCM doping), high thermal stability (T<sub>g</sub>: 100-400 °C), good thermo-optic property, high solvent and humid resistance, and excellent mechanical flexibility. The combination of processability and performance in these PFCB-containing thermoset materials make them as ideal candidates for the fabrication of high-performance polymeric planar lightwave circuit components with the applications in the telecom and datacom optical networks.