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A system for' producing 300 us bursts ofi lo1' metal atoms. with 3 'eV .average. energy is described. It is shown that.'-th'i's. system can be successfully used to introduce impurities'into '... .. . : : CTR oriented tokamaks for transport. and con£ inement studi'es .-. .

The limited flux and selectivities of current carbon dioxide membranes and the high costs associated with conventional absorption-based CO2 sequestration call for alternative CO2 separation approaches. Here we describe an enzymatically active, ultra-thin, biomimetic membrane enabling CO2 capture and separation under ambient pressure and temperature conditions. The membrane comprises a ~18-nm-thick close-packed array of 8 nm diameter hydrophilic pores that stabilize water by capillary condensation and precisely accommodate the metalloenzyme carbonic anhydrase (CA). CA catalyzes the rapid interconversion of CO2 and water into carbonic acid. By minimizing diffusional constraints, stabilizing and concentrating CA within the nanopore array to a concentration 10× greater than achievable in solution, our enzymatic liquid membrane separates CO2 at room temperature and atmospheric pressure at a rate of 2600 GPU with CO2/N2 and CO2/H2 selectivities as high as 788 and 1500, respectively, the highest combined flux and selectivity yet reported for ambient condition operation.

On a porous substrate, regular atomic layer deposition (ALD) not only takes place on top of the substrate but also penetrates into the internal porosity. Here we report a plasma-assisted process in which the ALD precursors are chosen to be non-reactive unless triggered by plasma, so that ALD can be spatially defined by the supply of plasma irradiation. Since plasma cannot penetrate within the internal porosity, ALD has been successfully confined to the immediate surface. This not only gives a possible solution for sealing of porous low dielectric constant films with a conformal layer of nm-scale thickness, but also enables us to progressively reduce the pore size of mesoporous materials in a sub-Å/cycle fashion for membrane formation.As device dimensions in semiconductor integrated circuits (ICs) continue to shrink, low dielectric constant (low-k) materials are needed as interlevel dielectrics (ILD) to mitigate issues caused by reduced line widths and line-to-line spacings such as increasing RC-delay. To satisfy the technical requirements established by the microelectronics roadmap (where k values < 2 are ultimately specified), future generation ILD materials must incorporate porosity. However, the pores, typically on the order of angstroms to a few nanometers and interconnected at elevated porosities, can trap moisture, gas precursors and other contaminants in subsequent

The electrochemical behavior of tungsten during chemical mechanical polishing (CMP) was observed in order to investigate a proposed blanket passivation and abrasion mechanism for tungsten removal. The experiments were performed in a cell that allowed electrochemical measurements to be made during polish. Polish rates were determined from the same samples used in the cell. Alumina-based polish slurries containing potassium iodate, ferric nitrate, or ammonium persulfate were used. DC polarization experiments show no evidence of passive film formation on the tungsten duiing polish. Tungsten oxidation rates measured during polish account for removal rates that are ito 2 orders of magnitude below the measured polish rate. Values of the charge-transfer resistance (measured by ac impedance spectroscopy) during polish are ito 2 orders of magnitude higher than expected from the polish rate, thus corroborating the dc-based data. Polish rates under potentiostatic conditions were also measured. The current required to maintain the metal anodic of the open-circuit potential is well below the current expected from measured polish rates, assuming complete oxidation of the tungsten. The polish rate during cathodic potentiostatic conditions (-0.5 V with regard to the open-circuit potential) was similar to the polish rate at open circuit. We conclude that the formation of a blanket passive layer does not significantly contribute to tungsten removal during CMP. InfroductionChemical mechanical polishing (CMP) is the most effective and now the predominant method for the removal of excess tungsten (W) deposited by nonselective chemical vapor deposition (CVD) for the formation of contacts and vias used in integrated circuit (IC) multilevel interconnects. Figure la depicts the CVD tungsten film and patterned oxide prior to polish. Figure ib depicts the same surface after CMP. The majority of W CMP research to date has focused on empirical cause and effect relationships in which process variables, such as slurry composition, pad type, applied pressures, and platen and carrier speeds, are empirically modeled. These empirical models allow for adequate manufacturing process control; however, they provide little information on the fundamental * Electrochemical Society Active Member.Oxide Fig. 1. The result of a blanket tungsten deposition is shown in the top sketch. The tungsten has been deposited in the vias opened in the inter-level dielectric, but is also present as a blanket film on the surface. The excess tungsten has been polished back to the interlevel dielectric in the bottom sketch.tungsten removal mechanisms that occur during polish. Clearer understanding of the removal mechanism(s) will benefit next-generation designs of slurries and pads and will improve W CMP manufacturing processes.In this work we investigate the role of tungsten oxidation and passive film formation in the mechanism of tungsten removal during CMP, by comparing measurements of the electrochemical behavior of the CVD tungsten film with tungsten removal rates obta...

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We report atomic layer deposition of an ultrathin hybrid organic/inorganic film on a porous support and its conversion to a high flux, high selectivity membrane. Through chemical passivation of the internal support porosity and remote oxygen plasma activation of the support surface, ALD of a bis(triethoxysilyl)ethane precursor is confined to the immediate surface of the support, allowing formation of a 5 nm thick film spanning the underlying porosity. UV/ozone removal of the C2 porogen creates a microporous membrane with a He/SF6 selectivity >104 and a substantial He flux of 5.3 sccm/bar·cm2. Prior to conversion, these ultrathin films are of interest as low k dielectric sealing layers. Use of bridging ligands with other shapes and sizes should enable generalization of this approach to other demanding separation problems.

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