17 research outputs found
Process for preparation of chiral 2-amino-1-(6-fluoro-3,4-dihydrobenzopyran-2-yl)ethanol. 2006)
No full textProcess for preparation of chiral 2-(2,2-dimethyl-1,3-dioxolan-4-yl)-6-fluoro-2,3-dihydrobenzopyran-4-one
No full textPolycarbonate based nonchemically amplified photoresists for extreme ultraviolet lithography
No full textSome initial EUVL patterning results for polycarbonate based non-chemically amplified resists are presented. Without full optimization the developer a resolution of 60 nm line spaces could be obtained. With slight overexposure (1.4 x E-0) 43.5 nm lines at a half pitch of 50 nm could be printed. At 2x E-0 a 28.6 nm lines at a half pitch of 50 nm could be obtained with a LER that was just above expected for mask roughness. Upon being irradiated with EUV photons, these polymers undergo chain scission with the loss of carbon dioxide and carbon monoxide. The remaining photoproducts appear to be non-volatile under standard EUV irradiation conditions, but do exhibit increased solubility in developer compared to the unirradiated polymer. The sensitivity of the polymers to EUV light is related to their oxygen content and ways to increase the sensitivity of the polymers to 10 mJ cm(-2) is discussed
Patterning of tailored polycarbonate based non-chemically amplified resists using extreme ultraviolet lithography
No full textA series of high-performance polycarbonates has been prepared with glass-transition temperatures and decomposition temperatures that are tunable by varying-repeat-unit chemical structure. Patterning by taking advantage of a molecular-weight solubility switch has been achieved with extreme ultraviolet lithography and the importance of resist-developer interactions has been demonstrated
Development of polymers for non-CAR resists for EUV lithography
No full textThree strategies for approaching the design and synthesis of non-chemically amplified resists (non-CARs) are presented. These are linear polycarbonates, star polyester-blk-poly(methyl methacrylate) and comb polymers with polysulfone backbones. The linear polycarbonates were designed to cleave when irradiated with 92 eV photons and high Tg alicyclic groups were incorporated into the backbone to increase Tg and etch resistance. The star block copolymers were designed to have a core that is sensitive to 92 eV photons and arms that have the potential to provide properties such as high Tg and etch resistance. Similarly the polysulfone comb polymers were designed to have an easily degradable polymer backbone and comb-arms that impart favorable physical properties. Initial patterning results are presented for a number of the systems
Controlled polymerisation of lactide using an organo-catalyst in supercritical carbon dioxide
No full textThe controlled, ring-opening polymerisation of DL-lactide in supercritical carbon dioxide (scCO(2)) using benzyl alcohol as an initiator and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as an organo-catalyst, is reported. Despite reports of DBU being efficiently converted to a carbonate salt in the presence of a proton source, it was found that DBU was still an efficient catalyst for the ring opening polymerisation of DL-lactide. Matrix-assisted laser desorption ionisation time of flight mass spectroscopy and H-1 nuclear magnetic resonance analysis demonstrated that end-group fidelity was maintained on the resulting polymer and significant transesterification was not observed under anhydrous conditions. We report a truly `green' process for the synthesis of polylactic acid (PLA) with the total absence of potentially toxic organic solvents and inorganic catalysts. In addition, the reaction in scCO(2) is conducted at temperatures much lower than that required for bulk polymerisation of LA
Control of the orientation of symmetric poly(styrene)-block-poly(D,L-lactide) block copolymers using statistical copolymers of dissimilar composition
No full textThe interactions of block copolymers with surfaces can be controlled by coating those surfaces with appropriate statistical copolymers. Usually, a statistical copolymer comprised of monomer units identical to those of the block copolymer is used; that is, typically a poly(styrene)-stat-poly(methyl methacrylate) (PS-stat-PMMA) is used to direct the alignment of poly(styrene),block-poly(methyl methacrylate) (PS-block-PMMA), and poly(styrene)-stat-poly-(2-vinylpyridine) (PS-stat-P2VP) has been used for poly(styrene)-block-poly(2-vinylpyridine) (PS-block-P2VP). Reports of controlling the orientation of block copolymers with statistical copolymers with a dissimilar composition are limited. Here, we demonstrate that this method can be further extended to show that PS-stat-PMMA can be used to control the wetting properties of poly(styrene)-block-poly(D,L-lactide) (PS-block-PDLA). Surfaces were modified with a series of cross-linked PS-stat-PMMA-stat-glycidyl methacrylate terpolymers, and the surface chemistries and energies were assessed using angle-dependent X-ray photoelectron spectroscopy and the two-liquid harmonic method, respectively. From these experiments, an expected neutral compositional window was identified for symmetrical PS-block-PDLA. Moreover, high-resolution SEMI AD-XPS, and grazing-incidence SAXS measurements were used to evaluate the morphology of PS-block-PDLA as a function of the surface composition of the underlying cross linked copolymer films, and the neutral composition was found to range from 32 to 38 mol % of PS, in the bulk polymer. Ultimately, we demonstrated the determination of nonpreferential surface compositions that allow the self assembly of lamellae with sizes in the sub 10 nm regime that are oriented perpendicular to the substrate. These findings have important implications for the use of PS-block-PDLA block copolymers in directed self assembly, most specifically in advanced lithographic processes
