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An oxygen-assisted hydrocarbon chemical vapor deposition method is developed to afford large-scale, highly reproducible, ultra-high-yield growth of vertical single-walled carbon nanotubes (V-SWNTs). It is revealed that reactive hydrogen species, inevitable in hydrocarbon-based growth, are damaging to the formation of sp 2 -like SWNTs in a diameter-dependent manner. The addition of oxygen scavenges H species and provides a powerful control over the C͞H ratio to favor SWNT growth. The revelation of the roles played by hydrogen and oxygen leads to a unified and universal optimum-growth condition for SWNTs. Further, a versatile method is developed to form V-SWNT films on any substrate, lifting a major substrate-type limitation for aligned SWNTs.nanomaterials ͉ hydrocarbon chemistry ͉ plasma ͉ sp 2 -sp 3 carbon ͉ catalysis C arbon nanotubes in aligned forms (1-6) are interesting for various scientific and practical applications ranging from electronics to biological devices. Although several chemical vapor deposition (CVD) methods have been developed to grow vertically aligned multiwalled carbon nanotubes, growth of vertical single-walled carbon nanotubes (V-SWNTs) is still in an early stage (7,8). The formation of nanotube vertical films is indicative of high-yield growth from densely packed catalytic particles. That is, almost every particle produces a nanotube, and bundling of neighboring tubes leads to collective vertical growth. A key element in a recent ethylene CVD method that has obtained V-SWNT growth is the addition of Ϸ150 ppm water vapor (8). Another method that has obtained V-SWNT growth is an alcohol CVD method using ethanol as the carbon feedstock. In both cases, the key role played by the oxygen-containing species is suggested to be oxidation of amorphous carbon to facilitate SWNT growth.Although we have made an effort to use both the waterassisted and alcohol CVD growth methods, we have been unable to obtain vertically aligned SWNTs, which indicates the narrow parameter space and growth window of these methods. Also, the specific roles played by the oxygen-containing species remain speculative and require further investigation. A more detailed understanding could lead to improved and more reproducible growth conditions. Here, we present a molecular oxygen-assisted plasma-enhanced CVD (PECVD) growth of V-SWNTs at the full 4-inch wafer scale. We find that adding oxygen (Ϸ1%) to methane in the PECVD affords highly reproducible growth of densely packed SWNTs. Control experiments and knowledge from previous diamond PECVD work suggest that the key role played by oxygen in the high-yield SWNT growth is to balance C and H radicals and, specifically, to provide a C-rich and H-deficient condition to favor the formation of sp 2 -like graphitic SWNT structures. We reveal that reactive hydrogen species are generally unfavorable to SWNT formation and growth and can etch preformed SWNTs. The negative role of hydrogen and the positive role of oxygen have important implications to SWNT growth in general by various me...

Abstract-Passivation of Ge has been a critical issue for Ge MOS applications in future technology nodes. In this letter, we introduce ozone-oxidation to engineer Ge/insulator interface. Interface states (D it ) values across the bandgap and close to conduction bandedge were extracted using conductance technique at low temperatures. D it dependency on growth conditions was studied. Minimum D it of of 3x10 11 cm -2 V -1 was demonstrated. Physical quality of the interface was investigated through Ge 3d spectra measurements. We found that the interface and D it is strongly affected by the distribution of oxidation states and quality of the suboxide.

Design of notched gate processes in high density plasmasOn the origin of the notching effect during etching in uniform high density plasmas Numerical simulation was used to study both surface charging and ion trajectory distortion during submicron patterning in high density plasma etching. The plasma was assumed uniform and the cause for the surface charging was the directionality difference between ions and electrons. The role of ion transit time effects on the ion energy distribution function was also considered, while the effect of discharging currents such as through insulators was not included. Using a Monte Carlo sheath simulator, a Poisson equation solver, and an ion/electron trajectory simulator, the steady state potential distribution and ion trajectories were calculated for various line-and-space structures and plasma conditions where notching, which is a local sidewall etching, has been observed after the overetching part of polysilicon etching processes. The results show significant positive charging at the bottom of high aspect ratio spaces which depends on the ion energy distribution function. Notching at the bottom of an outermost polysilicon line before a wide space is the result of ion deflection toward the line which has the lower potential from receiving more electrons from a side facing the wide space. The simulator was validated using previously reported electron cyclotron resonance etcher notching results. It was found that the calculated potential difference between the bottom of a space and the adjacent line shows the same qualitative dependence on the wide space width as experimental notch depth results show. In addition, these potential differences are large enough to substantially increase the ion flux at regions where notching occurs for the ion energy distribution function for the plasma conditions used. Thus this shows aspect ratio dependent charging effects which are not dependent on initial plasma nonuniformity.

A realistic assessment of future interconnect performance is addressed, specifically, by modeling copper (Cu) wire effective resistivity in the light of technological and reliability constraints. The scaling-induced rise in resistance in the future may be significantly exacerbated due to an increase in Cu resistivity itself, through both electron surface scattering and diffusion barrier effect. The impact of these effects on resistivity is modeled under various technological conditions and constraints. These constraints include the interconnect operation temperature, the effect of copper-diffusion barrier thickness and its deposition technology, and the quality of interconnect/barrier interface. Reliable effective resistivity trends are established at various tiers of interconnects, namely, at the local, semiglobal, and global levels. Detailed implications of the effect of resistivity trends on performance are addressed in the second part of this work.