Glycans have important roles in living organisms with their structural diversity. Thus, glycomics, especially aspects involving the assignment of functional glycans in a high-throughput manner, has been an emerging field in the postproteomics era. To date, however, there has been no versatile method for glycan profiling. Here we describe a new microarray procedure based on an evanescent-field fluorescence-detection principle, which allows sensitive, real-time observation of multiple lectin-carbohydrate interactions under equilibrium conditions. The method allows quantitative detection of even weak lectin-carbohydrate interactions (dissociation constant, K(d) > 10(-6) M) as fluorescent signals for 39 immobilized lectins. We derived fully specific signal patterns for various Cy3-labeled glycoproteins, glycopeptides and tetramethylrhodamine (TMR)-labeled oligosaccharides. The obtained results were consistent with the previous reports of glycoprotein and lectin specificities. We investigated the latter aspects in detail by frontal affinity chromatography, another profiling method. Thus, the developed lectin microarray should contribute to creation of a new paradigm for glycomics.
Low dielectric constant (low-k) films have been widely used as insulating materials in ultra-large-scale integrated circuits. Low-k films receive heavy damage during the plasma processes of etching or ashing, resulting in an increase in their dielectric constant. In order to realize damage-free plasma processes for low-k films, it is essential to determine the influence of radiation, radicals, and ions emitted in the plasma process on the characteristics of low-k films. We have developed a technique to evaluate the influence of radiation, radicals, ions, and their synergies on films in real plasma processes and have named it pallet for plasma evaluation (PAPE). Using the PAPE, plasma-induced damage on porous SiOCH films were investigated in dual-frequency capacitively coupled H2∕N2 plasmas. The damage was characterized by ellipsometry, Fourier-transform infrared spectroscopy, and thermal desorption spectroscopy. On the basis of the results, the damage mechanisms associated with vacuum ultraviolet (VUV) and UV radiation, radicals, and ions were clarified. The damage was caused not only by ions and radicals but also by VUV and UV radiation emitted by the plasmas. Moreover, it was found that the synergy between the radiation and the radicals enhanced the damage.
This study describes the development of a compact measurement technique for absolute carbon (C) atom density in processing plasmas, using vacuum ultraviolet absorption spectroscopy (VUVAS) employing a high-pressure CO2 microdischarge hollow-cathode lamp (C-MHCL) as the light source. The characteristics of the C-MHCL as a resonance line source of C atoms at 165.7 nm for VUVAS measurements of the absolute C atom density are reported. The emission line profile of the C-MHCL under typical operating conditions was estimated to be the Voigt profile with a ΔνL/ΔνD value of 2.5, where ΔνL is the Lorentz width and ΔνD is the Doppler width. In order to investigate the behavior of C and H atoms in the processing plasma used for the fabrication of two-dimensional nanographene sheet material, measurements of the atom densities were carried out using the VUVAS technique. The H atom density increased with increasing pressure, while the C atom density was almost constant at 5×1012 cm−3. The density ratio of C to H atoms in the plasma was found to influence the morphology of carbon nanowalls (CNWs). With increasing H/C density ratio, the growth rate decreased and the space between the walls of the CNWs became wider.
Superpositioning of negative dc bias in dual-frequency capacitively coupled plasmas (dc-superposed (DS)-CCP) was realized for the selective etching of carbon-doped silicon oxide (SiOCH) films over carbon-doped amorphous silicon (SiC) films, while the dc bias exceeded about −800 V. When a dc bias of −1200 V was superposed on 60 MHz VHF power on the top electrode opposed to a wafer on the bottom electrode biased with 13.56 MHz power, a selectivity of above 50 for SiOCH over SiC was obtained. From characterization of the plasma density and various chemical species in the gaseous phase, such as CF2, CF and atomic N, the density of CF2 significantly decreased with the application of dc bias ranging from −800 to −1200 V. This indicated that CF2 radicals were consumed at the surface of the counter electrode which was made of silicon. The bulk densities of the species including CF2 were decreased, especially due to excess surface loss caused by the bombardment of highly energetic ions accelerated by the superposed dc bias, as well as the rf sheath for the superposition of the negative dc bias. The DS-CCP technology is thus concluded to be indispensable for yielding highly selective etching of SiOCH over SiC.
Articles you may be interested inEffects of plasma and vacuum-ultraviolet exposure on the mechanical properties of low-k porous organosilicate glass J. Appl. Phys. 116, 044103 (2014); 10.1063/1.4891501Plasma damage effects on low-k porous organosilicate glass Plasma-induced damage to porous SiOCH ͑p-SiOCH͒ films during organic resist film ashing using dual-frequency capacitively coupled O 2 plasmas was investigated using the pallet for plasma evaluation method developed by our group. The damage was characterized by ellipsometry and Fourier-transform infrared spectroscopy. Individual and synergetic damage associated with vacuum ultraviolet ͑VUV͒ and UV radiation, radicals, and ions in the O 2 plasma were clarified. It was found that the damage was caused not only by radicals but also by synergetic reactions of radicals with VUV and UV radiation emitted by the plasmas. It is noteworthy that the damage induced by plasma exposure without ion bombardment was larger than the damage with ion bombardment. These results differed from those obtained using an H 2 / N 2 plasma for resist ashing. Finally, the mechanism of damage to p-SiOCH caused by O 2 and H 2 / N 2 plasma ashing of organic resist films is discussed. These results are very important in understanding the mechanism of plasma-induced damage to p-SiOCH films.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.