TY - JOUR TI - "dry" lithography using liquid and supercritical carbon dioxide based chemistries and processes AU - Hoggan, EN AU - Wang, K AU - Flowers, D AU - DeSimone, JM AU - Carbonell, RG T2 - IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING AB - Novel carbon dioxide (CO/sub 2/) soluble photoresists were synthesized based on random copolymers of 1,1-dihydroperfluorooctylmethacrylate and 2-tetrahyrdopyranyl methacrylate. These resins, along with specially designed CO/sub 2/-soluble photoacid generators, were utilized to demonstrate the potential for a new "dry" lithographic process. Photoresist spin casting, development, and stripping were all carried out using only liquid and supercritical CO/sub 2/ as the processing medium. A novel high-pressure spin coating process was used to deposit the photoresist films. Parameters such as resist sensitivity, contrast, and resolution were investigated. Wafers were imaged using both 248and 193-nm radiation, demonstrating the potential of this new photoresist platform for use as a sustainable technology for the microelectronics industry. DA - 2004/11// PY - 2004/11// DO - 10.1109/tsm.2004.837002 VL - 17 IS - 4 SP - 510-516 SN - 1558-2345 KW - liquid and supercritical carbon dioxide KW - lithography KW - photoacid generator KW - photoresist KW - resist contrast KW - resist sensitivity ER - TY - JOUR TI - High-pressure dynamic light scattering of poly(ethylene-co-1-butene) in ethane, propane, butane, and pentane at 130 degrees C and kilobar pressures AU - Kermis, TW AU - Li, D AU - Guney-Altay, O AU - Park, IH AU - Zanten, JH AU - McHugh, MA T2 - MACROMOLECULES AB - Poly(ethylene-co-1-butene) diffusion in ethane, propane, butane, and pentane indicates that ethane solutions are remarkably different. For propane, butane, and pentane the dynamic second virial coefficient, kD, is negative near the phase boundary, increases rapidly to positive values within ∼100 to 200 bar of the respective phase boundary, and approaches a constant value at high pressures. For ethane, kD is also negative near the phase boundary; it increases at a slower rate and becomes only slightly greater than zero. kD for all four solvents superpose when plotted against “methyl” molar density, suggesting thermodynamic interactions rather than hydrodynamic forces dominate. For propane, butane, and pentane the hydrodynamic radius, RH, also starts at a low value near the phase boundary and increases to the same value for all three alkanes. For ethane RH is ∼30% smaller than those for the higher alkanes, reflecting the poor quality of ethane even 1000 bar above the phase boundary. DA - 2004/11/30/ PY - 2004/11/30/ DO - 10.1021/ma0487103 VL - 37 IS - 24 SP - 9123-9131 SN - 1520-5835 ER - TY - JOUR TI - Brownian motion of colloidal spheres in aqueous PEO solutions AU - Zanten, JH AU - Amin, S AU - Abdala, AA T2 - MACROMOLECULES AB - The Brownian motion of colloidal spheres in aqueous poly(ethylene oxide) (PEO) solutions ranging in concentration from 0.2 to 15 wt % is measured with diffusing wave spectroscopy over more than 6 decades of time. The measured colloidal sphere mean-squared displacements are shown to satisfy the generalized Stokes−Einstein relation that relates the particle mean-squared displacement to the polymer solution shear modulus as the microrheological creep compliance calculated from the colloidal sphere Brownian motion was found to agree with that measured by mechanical rheometry. The microrheological zero shear viscosity concentration dependence for the entangled solution regime, η ∼ c4.7, is in agreement with that reported by others from mechanical rheometry measurements on polymer−good solvent solutions and is stronger than the tube model prediction, η ∼ c3.9. Essentially the entire deviation between the predicted and measured entangled solution regime zero shear viscosity concentration dependence is accounted for in the difference between the predicted, τ ∼ c1.6, and measured, τ ∼ c2.3, terminal relaxation time concentration dependence as the predicted, G ∼ c2.3, and measured, G ∼ c2.4, plateau modulus scaling at the terminal relaxation time are in excellent agreement. A power-law viscoelastic “plateau” region is observed to persist to frequencies of at least 105 s-1, thereby extending knowledge of polymer solution dynamics by nearly 3 decades of frequency. Interestingly, the high-frequency shear modulus was found to scale as G ∼ c4.5, not as G ∼ c2.3. DA - 2004/5/18/ PY - 2004/5/18/ DO - 10.1021/ma035250p VL - 37 IS - 10 SP - 3874-3880 SN - 1520-5835 ER - TY - JOUR TI - A hexamer peptide ligand that binds selectively to staphylococcal enterotoxin B: isolation from a solid phase combinatorial library AU - Wang, G AU - De, J AU - Schoeniger, JS AU - Roe, DC AU - Carbonell, RG T2 - JOURNAL OF PEPTIDE RESEARCH AB - Abstract: By screening a solid‐phase combinatorial peptide library, a short peptide ligand, YYWLHH, has been discovered that binds with high affinity and selectivity to staphylococcal enterotoxin B (SEB), but only weakly to other SEs that share sequence and structural homology with SEB. Using column affinity chromatography with an immobilized YYWLHH stationary phase, it was possible to separate SEB quantitatively from Staphylococcus aureus fermentation broth, a complex mixture of proteins, carbohydrates and other biomolecules. The immobilized peptide was also used to purify native SEB from a mixture containing denatured and hydrolyzed SEB, and showed little cross‐reactivity with other SEs. To our knowledge this is the first report of a highly specific short peptide ligand for SEB. Such a ligand is a potential candidate to replace antibodies for detection, removal and purification strategies for SEB. DA - 2004/8// PY - 2004/8// DO - 10.1111/j.1399-3011.2004.00170.x VL - 64 IS - 2 SP - 51-64 SN - 1397-002X KW - affinity adsorption KW - combinatorial peptide library KW - peptide ligands KW - staphylococcal enterotoxin B ER - TY - JOUR TI - Deposition of thin polymeric films from liquid carbon dioxide using a high-pressure free-meniscus coating process AU - Novick, BJ AU - DeSimone, JM AU - Carbonell, RG T2 - INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH AB - Free-meniscus coating processes can be used to deposit a wide variety of coatings. However, the physical properties of the coating solutions often lead to the deposition of nonuniform films. Recently, it has been recognized that compressed carbon dioxide can be used as an environmentally benign solvent for industrial processes. We investigate the use of liquid carbon dioxide as the solvent in free-meniscus coating processes because its physical properties are much different from standard coating solvents. The surface tension and viscosity of liquid carbon dioxide are an order of magnitude smaller than those of typical solvents. Additionally, the density of liquid carbon dioxide is strongly dependent on temperature and pressure. The Tallmadge four-force inertial theory is used to demonstrate that these unique physical properties will result in the formation of thinner films at the same withdrawal velocities as those used with conventional solvents. We then demonstrate experimentally that process variables can be controlled in a high-pressure coating chamber to deposit films of a perfluoropolyether lubricant with controlled thickness in the range of 25−350 Å on a silicon surface with a native oxide. It is shown that the withdrawal velocity, polymer solution concentration, and evaporation rate can be used to control the coating process to produce submicron films on a surface. DA - 2004/1/21/ PY - 2004/1/21/ DO - 10.1021/ie030688z VL - 43 IS - 2 SP - 515-524 SN - 0888-5885 ER - TY - JOUR TI - Applications of "dry" processing in the microelectronics industry using carbon dioxide AU - Jones, CA AU - Zweber, A AU - DeYoung, JP AU - McClain, JB AU - Carbonell, R AU - DeSimone, JM T2 - CRITICAL REVIEWS IN SOLID STATE AND MATERIALS SCIENCES AB - ABSTRACT Condensed carbon dioxide (CO2) has emerged as a leading enabler of advanced semiconductor manufacturing processes. By exploiting the physical properties of CO2, some of the current challenges encountered in microelectronics processing related to shrinking feature sizes and materials compatibility have been addressed. Furthermore, the potential for reduction of chemicals used in processing is realized. Applications of CO2 in microelectronics operations such as wafer cleaning, spin-coating, development, and stripping of photoresists, drying, low-k film preparation and repair, etching, and metal deposition are discussed. DA - 2004/// PY - 2004/// DO - 10.1080/10408430490888968 VL - 29 IS - 3-4 SP - 97-109 SN - 1547-6561 KW - supercritical fluids KW - semiconductors KW - cleaning KW - etching KW - phoioresist KW - stripping. KW - drving KW - low-k KW - metal deposition. ER - TY - JOUR TI - Impact of cold and cold-acid stress on poststress tolerance and virulence factor expression of Escherichia coli O157: H7 AU - Elhanafi, D. AU - Leenanon, B. AU - Bang, W. AU - Drake, M. A. T2 - Journal of Food Protection AB - The effect of extended cold or cold-acid storage of Escherichia coli O157:H7 on subsequent acid tolerance, freeze-thaw survival, heat tolerance, and virulence factor (Shiga toxin, intimin, and hemolysin) expression was determined. Three E. coli O157:H7 strains were stressed at 4 degrees C in TSB or pH 5.5 TSB for 4 weeks. The acid (TSB [pH 2.0] or simulated gastric fluid [pH 1.5]) tolerance, freeze-thaw (-20 degrees C to 21 degrees C) survival, and heat (56 degrees C) tolerance of stressed cells were compared with those of control cells. The beta-galactosidase activities of stressed and control cells containing a lacZ gene fusion in the stx2, eaeA, or hlyA gene were determined following stress in TSB or pH 5.5 TSB at 37 degrees C and in the exponential and stationary phases. Cold and cold-acid stresses decreased acid tolerance (P < 0.05), with a larger decrease in acid tolerance being observed after cold stress than after cold-acid stress (P < 0.05). Cold stress increased freeze-thaw survival for all three strains (P < 0.05). Prior cold or cold-acid stress had no effect on virulence factor production (P > 0.05), although growth in acidic media (pH 5.5) enhanced eaeA and hlyA expression (P < 0.05). These results indicate that the prolonged storage of E. coli O157:H7 at 4 degrees C has substantial effects on freeze-thaw tolerance but does not affect subsequent virulence gene expression. DA - 2004/// PY - 2004/// DO - 10.4315/0362-028X-67.1.19 VL - 67 IS - 1 SP - 19-26 ER - TY - JOUR TI - Structural characterization of an intermolecular RNA-RNA interaction involved in the transcription regulation element of a bipartite plant virus AU - Guenther, RH AU - Sit, TL AU - Gracz, HS AU - Dolan, MA AU - Townsend, HL AU - Liu, GH AU - Newman, WH AU - Agris, PF AU - Lommel, SA T2 - NUCLEIC ACIDS RESEARCH AB - The 34‐nucleotide trans‐activator (TA) located within the RNA‐2 of Red clover necrotic mosaic virus folds into a simple hairpin. The eight‐nucleotide TA loop base pairs with eight complementary nucleotides in the TA binding sequence (TABS) of the capsid protein subgenomic promoter on RNA‐1 and trans‐activates subgenomic RNA synthesis. Short synthetic oligoribonucleotide mimics of the RNA‐1 TABS and the RNA‐2 TA form a weak 1:1 bimolecular complex in vitro with a Ka of 5.3 × 104 M–1. Ka determination for a series of RNA‐1 and RNA‐2 mimic variants indicated optimum stability is obtained with seven‐base complementarity. Thermal denaturation and NMR show that the RNA‐1 TABS 8mers are weakly ordered in solution while RNA‐2 TA oligomers form the predicted hairpin. NMR diffusion studies confirmed RNA‐1 and RNA‐2 oligomer complex formation in vitro. MC‐Sym generated structural models suggest that the bimolecular complex is composed of two stacked helices, one being the stem of the RNA‐2 TA hairpin and the other formed by the intermolecular base pairing between RNA‐1 and RNA‐2. The RCNMV TA structural model is similar to those for the Simian retrovirus frameshifting element and the Human immunodeficiency virus‐1 dimerization kissing hairpins, suggesting a conservation of form and function. DA - 2004/5// PY - 2004/5// DO - 10.1093/nar/gkh585 VL - 32 IS - 9 SP - 2819-2828 SN - 1362-4962 ER - TY - JOUR TI - Spin coating of photoresists using liquid carbon dioxide AU - Hoggan, EN AU - Flowers, D AU - Wang, K AU - DeSimone, JM AU - Carbonell, RG T2 - INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH AB - A novel high-pressure carbon dioxide (CO2) spin-coating apparatus was designed and constructed to produce high-quality thin films of CO2-soluble photoresists based on 1H,1H-perfluorooctyl methacrylate/tert-butyl methacrylate copolymers. Film thicknesses were correlated to various process variables including rotational speed, solution viscosity, and evaporative driving force. The effects of these operating conditions on the film thickness and uniformity were compared to those of a theoretical model adapted for spin coating in CO2. Excellent correlation was found between the theoretical predictions and observed film properties, with the final films being of sufficient quality for use in photolithography. The potential of this spin-coating process in CO2 for developing a novel “dry lithography” is discussed. DA - 2004/4/28/ PY - 2004/4/28/ DO - 10.1021/ie0308543 VL - 43 IS - 9 SP - 2113-2122 SN - 0888-5885 ER -